As far as it being too late, I think it depends what you get on the MCAT. I took mine in July, got my score back in august (31Q) and got my interview invites the same week I got my score back. The key for me was to have everything else submitted and to "only" be waiting for the updated MCAT score. I don'tknow if it is possible if you don't yet have any score... I had a prior 27 that I wanted to improve upon.
As far as study time, Early May-Early august may not be enough time if that's the only time you spend studying. I think your best bet is to start studying now in your spare time to try and get through some of the material, so that when you get to May you're just doing a more intensive review and can focus on practice tests.
Have you taken any practice tests to get a baseline score? Do you have a plan? Kaplan, TPR, etc? I did Kaplan, but I think just having the Kaplan books and online material would have been enough even without the classroom time.
The biggest advice I can give you from my personal experience is not to discount the verbal section. If you aren't a natural at comprehensive reading, then it may surprise you, but we're all different.
Good Luck!