The timetable is a great idea! You can even make cut offs for how late you will work and gradually move them earlier. A regular sleep schedule is also really important as if you go to sleep earlier you can wake up earlier and get more work done earlier in the day. Don't be afraid to give yourself breaks whilst you're working so you don't overwork and feel drained and make sure you give yourself time to relax before trying to sleep, whether that's watching a TV show or reading or listening to music.
Hope this helps,
Becky (Lancaster University Student Ambassador)