They also have special offers periodically for $99 USD / year, and that rate is locked in and will not go up. Just Google guitar tricks offers. I think that promotion runs fairly often but you have to look for it, I am not sure if they actively advertise it. That price is about the cost of two or three private lessons, so it is a really good deal.
It takes as long as it takes unless you quit - then it takes forever and you will never get there.