Fixed points first, then the rest

Start from what cannot move: classes, work shifts, a standing commitment. Those are the skeleton. Then place the two or three things that genuinely have to happen this week, and place them at the times you are actually good — most people have a few hours a day when hard work is possible and a great many when it is not.

Everything else goes on a list without a time attached. Not scheduled, just available. A plan with forty timed items is a fantasy; a plan with six timed items and a list is a week.