I took the August MCAT and it wasn't too late. Just make sure that everything else is in before you go and take the MCAT, then the scores will catch up to the rest of your application as soon as they are released. The down side is that you won't know your score before you send it to the medical schools, because it will just automatically be sent (because you'll check the option to have them released to your schools immediately, so that everything is in on time).
Anyway, if I were not a not-trad with a few years out of school already and very anxious to start school sooner rather than later, I might have wanted to wait another year, but I took the August MCAT, and made all the deadlines and was accepted. So, no need to worry.