Depends largely on where you are already with your transition and what therapist you see. If you're already living full time as a male then the process goes much quicker than if you walk in there still presenting as female.
Just remember their job isn't to hinder you. What they are doing is trying to make sure you know what you want (as not everything is reversible after you start T) and to make sure that you will be ok during this process.
I know a lot of guys want to rush it. You very well may walk out of the gender clinic with an endo appointment. I don't know. I would say 6 months is a good guess if you're young and just starting out.
Then again I'm 31 years old, been living full time for 14 years, and I got mine in one visit. It really is on a case by case basis.
