swepi wrote: I would suggest taking one test down off of the shelf and organizing what you need to know.
I agree. I found it really helpful to take one test before starting studying, to identify what my weakest areas were. (I knew I didn't remember much thermo or optics, but I was surprised to see how much E&M I got wrong, for example, I thought that was one of my stronger areas.) Since you have many months, by the time you start doing practice tests you have probably forgotten the specific questions anyways.
Once you've reviewed and feel comfortable with the basics, it might be a good idea to use the released tests mainly to get up to speed, as sadly ETS prefers someone who answers 100 questions and gets 30 wrong to someone who answers 50 and gets them all right.