The few years is just in my case!! well life got in the way, and then I had to make up the deficiency in OB, plus I moved states so I had to begin the whole cgfns process again lol but I would give it a good six months to a year to get everything done from CGFNS through to getting the ATT to take the NCLEX.
I didn't find a college to do it over here, but i'm sure there's one out there. Most aussies I know go through a uni in australia or Deakin.
Are you already here in the states?
I haven't taken the NCLEX yet. I am doing Saunders review. I would say that they do a lot of delegation and prioritisation which I didn't ever do in Uni exams. But each person will find different things challenging. Also memorising pages of normal lab values wasn't something I ever did...
Hope that helped