It’s up to u, but it’s important that you make a routine for revising. Don’t be revising at 3am when you feel like it then stop.
When I was doing GCSE I would revise for 4 hours. (Revise one hour , 30 min break , revise). If you feel that you revise in the afternoon better like I did or in the mornings I would suggest making a timetable and ensuring that you use these times to revise; then making your evenings free.