It is okay if you do not have an hour-by-hour schedule of what you do (recommended, though).
However, what would be wonderful is to have a routine of workout, meditation, studying, working, free time, walk, and everything else that is important to you.
If it is important to you, even if your schedule is a bit here and there, you will be able to get done with a good routine.
Routines prevent from riots, when schedule is simmering around a bit.