You can preheat by setting the timer before you get out of the car the night before.
Just select menu with the ignition on, select car systems, aux AC i think, set the time and date and tick the box.
The following day if you leave at the same time when you attempt to set the time and date it automatically updates the date so just back up tick the box and its set.
In order to schedule climate control and charging in the car, you will need to get the MMI Plus system that comes with the Technology Package/Navigation. If you didn't order this package, all scheduling can only be done through the e-tron connect app or etron.myaudiusa.com portal, both of which are not working right now.
See my post regarding logging to e-tron connect app or the web portal for US e-trons in a thread somewhere in this forum.