15 months.
Big mistake. I was fired from two jobs in the meantime because I was waiting to pass first, and putting up with the dysphoria in the meantime.
Yes, I did pass as soon as I went full-time, but the wait was seriously hellish. I should have gone full-time back at 7 months or so when I started passing consistently in a wig. But I was too stubborn to be forced to use something "fake" in order to pass, and ended up denying my own happiness because of that stubbornness.
I was expecting to somehow earn the right to be female. It was only after going full-time that I finally realized that I already was, and there was nothing to earn, and no magical switch that I had to wait for.