The way to get a lot of work done is to have many hours at a time to sit down in one place and study. If you are constantly jumping up and down to go to classes throughout the day, you will not get as much done as you would if you have all your classes at one time, leaving the rest of the day to focus strictly on studying. You will then have no disruptions, no pressure of racing against the clock, and thus no problem focusing on the task at hand. I personally feel that anything earlier is too early and will leave you aching for a nap throughout the day. Anything later, in my opinion, will deprive you of a full day of work.
Life being what it is, the perfect schedule is probably unobtainable.
Whatever you decide to do, don't go back to your dorm room. You will waste time walking back and forth, and it is virtually impossible to get any work done in the dorm because of the distractions of roommates, friends, the telephone, and the bed, commonly referred to by students as the black hole. The best advice I have is to pack a couple extra books in your bag, and find a quiet spot to study between classes. Believe it or not, at college, some students eat when it is convenient, not necessarily when they're hungry. I sometimes find myself eating when I am not so hungry just because I have no time later on in the day.