Are you using source books or study notes? The source stuff doesn't change much. The study notes can. That said, either way it can be done but you may have to fill in some gaps in the material either on-line or at a library. I used two-year old study notes for Level 1 and made it through. Depends on your background too.
So, it can be done, but you probably shouldn't tempt fate. Looking back I realize it was a bad idea.