I agree with Jeffort. The Princeton book definitely is not good. I studied independently and started about 2 months before the test. I used the Powerscore Bibles and LSAC's 10 Actual, Official LSAT PrepTests series (as well as The Next 10). As for how early to study, if you do a class, I would wait until closer to the test, but if you're independent, I can't say. Everyone studies differently independently. I would probably wait until closer to the test, but it's ultimately up to you.