OP, in my experience, Smart Preconditioning worked “okay.” To be fair, I gave it about three weeks and felt that maybe it did the right thing 60% of the time so perhaps I needed to be more patient. In the end, I decided that just turning on the heat 10 minutes before I got to the car did the trick for the mild Seattle climate. YMMV of course.
But if you’ve turned on Smart Preconditioning, and given it two months of training, I’d say it won’t work for you. Turn it off and go the manual route.
For the manual route to warm up the battery at a certain time, you can do via the Tesla app...though not as intuitively as I’d like yet. Instead of using the app to “Have the car warm and ready to go at 6:45 am” (which how it should work!) you have to calculate the charge time for your available battery, then use the app to “Start charging the car at 3:30 am” (or whatever time will get you to your desired percentage at 6:45 am). As long as you finish charging right about the time you need to leave, the battery will be warm and ready.
It’s an extra mental step that shouldn’t be necessary, so I hope Tesla will update the app with a better way to manage that soon!