Sorry but it really depends on your mastery of the material. It seems like you have a solid background so maybe you can get away with ~2 months of studying or so? I don't think you have to worry about preparing early since your classes should be preparing you. Just study for the few months before the test. I think the biggest thing is just to keep yourself motivated and pace so you don't burn out/ quit, so like 5-6 hours a day ? but this is also personal... Avg MCAT for top 30 is around mid thirties and should be attainable if you master the sciences, which are easier to prepare for imo.
I don't think course is necessary; Kaplan is a big rip off seriously. Just buy some ExamKracker books and self study. save money for application and interviews.
If you're confident, you can take in summer months (even July/Aug) after submitting primary; if not, take it by June so you have chance to retake if needed.. GL