From what I understand is, you're going to graduate in coming Dec, 2015 and you're planning to take the MCAT around April. If this is the case, I recommend taking the MCAT in late May. There is no point of taking the exam in April since AAMC registrations won't open until June. This would give you an extra month of studying. (I recommend starting now and studying during school if possible, even one hour a day will keep you going and that would be almost 9 months of studying).
for Content, every prep class has its strength and weakness. But as far as I know, Princeton and Berkeley are good from the reviews I've read.
For content review, go to
@mcatjelly signature. She has a full list of them and many are free.
Good luck!