Checking out your videos, you're not too far from where I was when I started with GT. I'm sure that the instructors will have a much better sense of where you should start, but if it were me and I were you, I'd start at the beginning even though a lot of the initial stuff might be repetitious -- you'll fly through the stuff you already know so it won't take much time and, again, based on my experience only, I was able to hone and solidfy things and correct some of my bad self-taught habits (not saying you have those, but I sure do!) before moving on to new things. And I think it also serves to orient in terms of the methodology that GT uses for teaching, which is on and of itself something to get familiar with before moving on to new things. (Also Lisa is amazing as a teacher, which is no small thing.)

I am continually surprised at how much there is to learn in Fundamentals I and II even coming to them with a solid basic knowledge of theory, strumming and chords.

I hope that helps!