Looking from the point of view of a Jagex employee, I'd say during school. If they resolve your IP address to a DNS somewhere in an area where the time you sleep is the time you're botting, they're going to suspect something.
Would it look better if you were botting eight hours every day from 12:00 AM to 8:00 AM or botting during 9:00 AM to 5:00 PM? Not everyone works, remember that.