What if you have a Canadian citizenship? Is it still 8 years?
>There's a 60 day wait period after you last enter on TN, and you cannot leave the country when the AOS
So, when I first get my TN visa, I cannot leave the country without any of those papers? How long does my first TN visa last and if that expires I have to wait for 60 days before I get a new one?
Your visa will initially be valid for 3 years. It can be extended a few times. Ideally you'd have at least a year left on your current visa when submitting the AOS application since you cannot reenter on TN once that happens.
Disclaimer: I'm not a lawyer, I'm going through the process now and using time spans quoted by my lawyers and my own research.