While I don't want to discount any of the advice prior to my response here, I do want to answer the original question. The Tesla app doesn't have a way to do what you want that I am aware of, but people definitely do this with the Tesla API and things like IFTT (a subscription webapp that could interact with the API to start and stop charging and/or change your scheduled charge time based on criteria and schedules you effectively program into it). While I haven't used IFTT, I believe it is supposed to be intuitive, so don't let hte word programming scare you. You could probably find examples that could lead you in the right direction for that option elsewhere on the web by choosing the appropriate search terms. While my google-fu is horrific, and there may be services other than IFTT that fall in the same category (automation, I believe), something like this might work: iftt tesla api charging
