Hi, I joined mid-December, newbie at 51, been practicing almost daily, and am up to the GT1 lessons on switching from Em to Am and D to Em. Taking a while for my fingers to respond the way I want them to, particularly going from Am to Em and having a clean sound on each chord!

I don't think there is a standard on how long all this should take, just practice until your are comfortable to move to the next lesson ;-)