Apply in september, with the highest cr+m combination single sitting. Check dus and check both fall and optional summer session. You will get a little boost if you took all three of bio, chem, and physics ; if you took 4years of a foreign language ; if you took calculus ; if over 4years 20 of your classes were either AP or honors (ib, de, and aice count also) . You can count classes taken senior year for these questions on the application. And then you have to be patient and wait till late January.