Agree completely with Jeff. I made it through GF1 and GF2 and was working on Accoustic when I was disrupted for about 9 months with a major move out of the country. When I finally picked up the guitar again I decided to go back over 1 and 2. What I found is that I was able to skim through pretty quickly and even if I began a lesson and was feeling like wow this is like starting over again, in the end I could get it in 1 or 2 sittings instead of 2 weeks or longer. I enjoyed it so much I plan to go over them again since they have been recently replaced with a new instructor.

Moral of the story is you will build your skill and dexterity throughout the lessons and when you go back that "thing" will be easier so don't stress about pushing forward and just focus on having fun and doing what you need to do to keep interested.