Through my own experimentation, I've come to the conclusion that this plugin, for whatever reason ignores the values placed in config.yaml and always has a 20 second delay. In this fork, I have hard coded a 0 second delay time so it initiates the connect sequence almost instantly. I'm successfully using this connected to Creality3D Version 1.1.3 mainboards that are running Marlin 2.0.X Bugfix that take approximately 5-6 seconds to finish booting to the status screen, also taking into account the fact that initiating the USB connection causes the mainboard to restart its boot sequence. This fork was made to run in combonation with @UnchartedBull's OctoDash and OctoPrint-PSUControl available in Octoprint's built in plugin repo, to switch a relay to power up the mainboard.
Have you noticed that if you load up the OctoPrint web page when your printer is off, the printer's port isn't in the list? Then when you turn on the printer you have to refresh the page to make it show up? This plugin fixes that.
It watches for the device to appear (when you turn it on) and then notifies all the web clients to refresh the list of ports.
It also (if you have autoconnect turned on), will automatically connect to the
printer (if the new port is the same as the one you've selected in connection
settings) after a reasonable (long) delay to wait for the printer to actually
come on. The default delay is 20 secs. It's settable in config.yaml, if
anybody uses this plugin besides me, I could be talked into a settings page.
Install via the Octoprint plugin manager by copying/pasting the below URL into the "... from URL" field and click install
https://github.com/mikekscholz/OctoPrint-PortLister/archive/master.zip
OR,
Download the zip file via the "Clone or Download" button and then use the plugin managers "browse" button to find where you saved the download on your computer. (personally I like keeping local copies of obscure forks so I dont have to hunt them down all the time)
In .octoprint/config.yaml, the autoconnect_delay can be configured to
something other than the default 20 seconds it takes my printer to boot up.
plugins:
portlister:
autoconnect_delay: 20