I would double check that your state will let you go for a PE without an engineering degree.
I'm taking the FE in October as well, and I'll be 5.5 years out of school at that point. Paging through my FERM, I discovered that while I remember statics, dynamics, mechanics of materials, etc. with no difficulty - things like math, chemistry, and E&M are going to take some serious review. I'm glad I'm starting my preparation now!
I did units last week and it was surprisingly difficult to handle English units again. My work as a mechanical engineer is virtually all in SI units (although I'm constantly doing ft to meter, lb to kg, and ft/min to m/sec conversions). I figure I ought to get used to working with English units and doing conversions now, because I hear the mechanical PE exam is virtually all English units.
I ordered a package from the infamous other board that is intended for those who have been out of school for a while. It has the FERM, an EIT Reference Manual, the solutions for the EIT Reference Manual, the NCEES supplied-reference handbook, and some flashcards. Overall the package seems like a good one except for maybe the flashcards. I really like the EIT Reference Manual. I take it to work and read material during my lunch break. For about 60-90 minutes in the evenings, I'm just sitting down with the FERM and the EIT Reference Manual and reviewing and doing problems. I'm using an approved calculator and only the NCEES handbook as a reference. My goal is to do EVERY practice problem in both the Reference Manual and the FERM - and then do them all again as October approaches. I really want to get through the FE on my first try, since it could be a few years before I manage to prep for the PE and take it.