That's a tough question to answer and entirely dependent on you. How well do you "cram"? How well do you have the basics down (strong math, good vocab, remember a bit of chemistry, etc)?
Studying for the PCAT can be really overwhelming, so I think a few hours each week and then a concerted push a few weeks before your test date is not a bad way to go. I've taken the PCAT and I HIGHLY recommend shelling out for the official practice exam offered by Pearson and their study guide. Out of all of the study guides I looked at, this was by far the biggest help. Let me tell you that if your vocab and reading skill aren't strong, the verbal portion of the PCAT is kind of a jerk. Start early. Also, the math is super heavy on word problems now so keep that in mind if it is a weak spot for you. But again, the Pearson materials were very helpful in this regard.
Given what sounds like dire warnings, I kind of did the same thing as you. A few hours here and there while I had a full class load then I studied my ass off about 1 month before the test (took it this last January) and I pulled a 93 composite.
Let me know if you have specific questions.
