I have many smart plugs like everyone here , but one was not scheduling correctly (I was setting up Christmas lights and reconnecting some kasas in storage) and one light/kasa plug combo though scheduled like the others , was going on and off at wrong times.

This 1 problem plug was defaulting to a wrong timezone, and syncing time in settings wasn't fixing the problem.  When I'd schedule sunset on, it would turn on 3 hours earlier because it was defaulting to dawson america timezone.

The fix: keep deleting and configuring till you get the name your device prompt.

delete the device, re-configure, and the key is.... Make sure you get to the point where kasa says success and name your device.  I kept getting a pop up in configuration that would take me to wifi settings and asking me to have the device recognized in my wifi settings (outside of the kasa app, on my phone).  If you see your device after set up with the TP ID you haven't fully configured it (you should get to a point where you call the plug holiday lights etc,).

Why it worked the one time:  no idea, might be a glitch.

The one thing I don't know is what was magical about the time it fully configured.  I'm guessing it's a glitch and just keep deleting the plug and reconfiguring until it goes to completion, I forget it's a step or two after getting the connection success notification, something like your device is ready 

Why didn't I use google home for scheduling? I like that the kasa app has the sunset/sunrise feature in scheduling lights on/off which I think moves scheduling in real time as days shorten minute by minute or vise versa as opposed to a fixed time. I don't think google home has a sunset feature.

Long post but I hope it helps the ocd smart crowd out there!  Stay healthy and happy !