diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index cbe6225..6853b5a 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -4,7 +4,9 @@ Changelog
 3.2.0 (unreleased)
 ------------------
 
-- Nothing changed yet.
+**Bug fixes**
+
+- Bypass storage when redirecting on old ``_since``
 
 
 3.1.0 (2020-09-22)
diff --git a/kinto_changes/views.py b/kinto_changes/views.py
index ab619e0..9953860 100644
--- a/kinto_changes/views.py
+++ b/kinto_changes/views.py
@@ -90,16 +90,14 @@ class Changes(resource.Resource):
     schema = ChangesSchema
 
     def __init__(self, request, context=None):
-        super(Changes, self).__init__(request, context)
+        # Bypass call to storage if _since is too old.
+        _handle_old_since_redirect(request)
+        # Inject custom model.
         self.model = ChangesModel(request)
-
-    @property
-    def timestamp(self):
-        return self.model.timestamp()
+        super(Changes, self).__init__(request, context)
 
     def plural_get(self):
         result = super().plural_get()
-        _handle_old_since_redirect(self.request)
         _handle_cache_expires(self.request, MONITOR_BUCKET, CHANGES_COLLECTION)
         return result
 
@@ -135,8 +133,13 @@ def _handle_old_since_redirect(request):
     See https://bugzilla.mozilla.org/show_bug.cgi?id=1529685
     and https://bugzilla.mozilla.org/show_bug.cgi?id=1665319#c2
     """
-    qs_since = request.validated["querystring"].get("_since")
-    if qs_since is None:
+    try:
+        # request.validated is not populated yet (resource was not instantiated yet,
+        # we want to bypass storage).
+        qs_since_str = request.GET.get("_since", "")
+        qs_since = int(qs_since_str.strip('"'))
+    except ValueError:
+        # Will fail later during resource querystring validation.
         return
 
     settings = request.registry.settings
@@ -240,13 +243,13 @@ def get_changeset(request):
         include_deleted = True
 
     if (bid, cid) == (MONITOR_BUCKET, CHANGES_COLLECTION):
-        model = ChangesModel(request)
+        # Redirect old since, on monitor/changes only.
+        _handle_old_since_redirect(request)
 
+        model = ChangesModel(request)
         metadata = {}
         timestamp = model.timestamp()
         changes = model.get_objects(filters=filters, include_deleted=include_deleted)
-        # Redirect old since, on monitor/changes only.
-        _handle_old_since_redirect(request)
 
     else:
         bucket_uri = instance_uri(request, "bucket", id=bid)