What time should I go to sleep?

Ok I get up a 6:30 every day because school starts at 8 but my bus comes at 7:38, so what time should I go to sleep? I'm 12, in year 7. Usually before bed I get in the shower at 7:30 pm, get out at 8, watch an episode of a tv show (half an hour which by then is 8:30,) read a book for 15 minutes, (8:45) and then go to sleep. Does that sound ok? And sometimes I also have trouble sleeping so what methods are good for getting sleep? I know there's a lot of questions but hey I'm curious :)