I did content for 10 weeks and then practice exams for 5. Realistically that 5 was more like 3 because the time was school-test heavy. I would say practice tests are the single most important thing you can do in studying. It is when you really begin to realize what you're weak on and clarify things that you had a flawed understanding of. I would say if you have a month to devote to just that then that's fine, but the more time the better. I kind of wished I had a little more time for it, but I can't really complain about my MCAT prep.
Studied hardcore from December-January, then took a FL twice a week in Feb. Then I put them up until May, when I did two a week again.
The idea being that in the 1-2 mos leading up to the test you are looking for your groove time-wise, and 4-5 mos before you are just learning about the test. The 4-5 mos part could be mostly supplanted by simple practice passages if need be, but most people feel compelled to take FLs (i did) until they feel more comfortable with the format.