During my first year I studied from 5:00 am - 8:00, then from 6:00 - 10:00. I never did work on weekends, except for Sunday night.
Things get so much better after the first year. During my second year I probably spent 2 hours a day preparing for class. This year I don't do much work at all. Last semester I read for the first two weeks, and then didn't open up a case book after that. I started studying for exams about a month before they began. Of course, I'm also in the middle of my class, so if grades are really important to you, you may want to work more than I did!