diff --git a/packages/react-client/src/ReactFlightClient.js b/packages/react-client/src/ReactFlightClient.js
index 1c2151362d89b..8bcabfb5563bb 100644
--- a/packages/react-client/src/ReactFlightClient.js
+++ b/packages/react-client/src/ReactFlightClient.js
@@ -2561,6 +2561,7 @@ function ResponseInstance(
   findSourceMapURL: void | FindSourceMapURLCallback, // DEV-only
   replayConsole: boolean, // DEV-only
   environmentName: void | string, // DEV-only
+  debugStartTime: void | number, // DEV-only
   debugChannel: void | DebugChannel, // DEV-only
 ) {
   const chunks: Map<number, SomeChunk<any>> = new Map();
@@ -2621,7 +2622,8 @@ function ResponseInstance(
       // Note: createFromFetch allows this to be marked at the start of the fetch
       // where as if you use createFromReadableStream from the body of the fetch
       // then the start time is when the headers resolved.
-      this._debugStartTime = performance.now();
+      this._debugStartTime =
+        debugStartTime == null ? performance.now() : debugStartTime;
       this._debugIOStarted = false;
       // We consider everything before the first setTimeout task to be cached data
       // and is not considered I/O required to load the stream.
@@ -2669,6 +2671,7 @@ export function createResponse(
   findSourceMapURL: void | FindSourceMapURLCallback, // DEV-only
   replayConsole: boolean, // DEV-only
   environmentName: void | string, // DEV-only
+  debugStartTime: void | number, // DEV-only
   debugChannel: void | DebugChannel, // DEV-only
 ): WeakResponse {
   return getWeakResponse(
@@ -2684,6 +2687,7 @@ export function createResponse(
       findSourceMapURL,
       replayConsole,
       environmentName,
+      debugStartTime,
       debugChannel,
     ),
   );
diff --git a/packages/react-markup/src/ReactMarkupServer.js b/packages/react-markup/src/ReactMarkupServer.js
index 0b35404cb80aa..6f1e35e6156eb 100644
--- a/packages/react-markup/src/ReactMarkupServer.js
+++ b/packages/react-markup/src/ReactMarkupServer.js
@@ -91,6 +91,9 @@ export function experimental_renderToHTML(
       undefined,
       undefined,
       false,
+      undefined,
+      undefined,
+      undefined,
     );
     const streamState = createFlightStreamState(flightResponse, null);
     const flightDestination = {
diff --git a/packages/react-server-dom-esm/src/client/ReactFlightDOMClientBrowser.js b/packages/react-server-dom-esm/src/client/ReactFlightDOMClientBrowser.js
index cfc8dcf5f1b25..371f08abc9a62 100644
--- a/packages/react-server-dom-esm/src/client/ReactFlightDOMClientBrowser.js
+++ b/packages/react-server-dom-esm/src/client/ReactFlightDOMClientBrowser.js
@@ -52,6 +52,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
 };
 
 function createDebugCallbackFromWritableStream(
@@ -103,6 +104,9 @@ function createResponseFromOptions(options: void | Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
diff --git a/packages/react-server-dom-esm/src/client/ReactFlightDOMClientNode.js b/packages/react-server-dom-esm/src/client/ReactFlightDOMClientNode.js
index 2bf32729472d2..78dce936158eb 100644
--- a/packages/react-server-dom-esm/src/client/ReactFlightDOMClientNode.js
+++ b/packages/react-server-dom-esm/src/client/ReactFlightDOMClientNode.js
@@ -57,6 +57,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Node.js client we only support a single-direction debug channel.
   debugChannel?: Readable,
 };
@@ -112,6 +113,9 @@ function createFromNodeStream<T>(
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 
diff --git a/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientBrowser.js b/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientBrowser.js
index 2f71ce2fa9597..0f0141e640988 100644
--- a/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientBrowser.js
+++ b/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientBrowser.js
@@ -129,6 +129,9 @@ function createResponseFromOptions(options: void | Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
@@ -205,6 +208,7 @@ export type Options = {
   temporaryReferences?: TemporaryReferenceSet,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
 };
 
 export function createFromReadableStream<T>(
diff --git a/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientEdge.js b/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientEdge.js
index f9c63ccbc3370..5c8d1023b2373 100644
--- a/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientEdge.js
+++ b/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientEdge.js
@@ -79,6 +79,7 @@ export type Options = {
   temporaryReferences?: TemporaryReferenceSet,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Edge client we only support a single-direction debug channel.
   debugChannel?: {readable?: ReadableStream, ...},
 };
@@ -107,6 +108,9 @@ function createResponseFromOptions(options?: Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
diff --git a/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientNode.js b/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientNode.js
index b874bcd7d44f5..fbc633a175321 100644
--- a/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientNode.js
+++ b/packages/react-server-dom-parcel/src/client/ReactFlightDOMClientNode.js
@@ -52,6 +52,7 @@ export type Options = {
   encodeFormAction?: EncodeFormActionCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Node.js client we only support a single-direction debug channel.
   debugChannel?: Readable,
 };
@@ -103,6 +104,9 @@ export function createFromNodeStream<T>(
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 
diff --git a/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientBrowser.js b/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientBrowser.js
index b4b84f1c41b23..b3d31bd1bbba9 100644
--- a/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientBrowser.js
+++ b/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientBrowser.js
@@ -51,6 +51,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
 };
 
 function createDebugCallbackFromWritableStream(
@@ -102,6 +103,9 @@ function createResponseFromOptions(options: void | Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
diff --git a/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientEdge.js b/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientEdge.js
index b994841be18b3..5517e0f73cf94 100644
--- a/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientEdge.js
+++ b/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientEdge.js
@@ -79,6 +79,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Edge client we only support a single-direction debug channel.
   debugChannel?: {readable?: ReadableStream, ...},
 };
@@ -109,6 +110,9 @@ function createResponseFromOptions(options: Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
diff --git a/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientNode.js b/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientNode.js
index f174f10c0b88f..6d117929df007 100644
--- a/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientNode.js
+++ b/packages/react-server-dom-turbopack/src/client/ReactFlightDOMClientNode.js
@@ -60,6 +60,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Node.js client we only support a single-direction debug channel.
   debugChannel?: Readable,
 };
@@ -114,6 +115,9 @@ function createFromNodeStream<T>(
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 
diff --git a/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientBrowser.js b/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientBrowser.js
index b4b84f1c41b23..b3d31bd1bbba9 100644
--- a/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientBrowser.js
+++ b/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientBrowser.js
@@ -51,6 +51,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
 };
 
 function createDebugCallbackFromWritableStream(
@@ -102,6 +103,9 @@ function createResponseFromOptions(options: void | Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
diff --git a/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientEdge.js b/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientEdge.js
index 63dae4954550a..bc4caac767fb8 100644
--- a/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientEdge.js
+++ b/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientEdge.js
@@ -79,6 +79,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Edge client we only support a single-direction debug channel.
   debugChannel?: {readable?: ReadableStream, ...},
 };
@@ -109,6 +110,9 @@ function createResponseFromOptions(options: Options) {
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );
 }
diff --git a/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientNode.js b/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientNode.js
index f174f10c0b88f..6d117929df007 100644
--- a/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientNode.js
+++ b/packages/react-server-dom-webpack/src/client/ReactFlightDOMClientNode.js
@@ -60,6 +60,7 @@ export type Options = {
   findSourceMapURL?: FindSourceMapURLCallback,
   replayConsoleLogs?: boolean,
   environmentName?: string,
+  startTime?: number,
   // For the Node.js client we only support a single-direction debug channel.
   debugChannel?: Readable,
 };
@@ -114,6 +115,9 @@ function createFromNodeStream<T>(
     __DEV__ && options && options.environmentName
       ? options.environmentName
       : undefined,
+    __DEV__ && options && options.startTime != null
+      ? options.startTime
+      : undefined,
     debugChannel,
   );