Whenever you feel like it. On the bright side, you are unlikely to be confronted in the men's room even if you don't pass yet. I used to use the men's room when presenting as a very effeminate female at clubs because the women's restrooms would run out of toilet paper. Other ladies would suffer though, and I'd be all: screw it, I'm using the men's. I'd walk in and guys at the urinals would look at me for about two seconds then go back to their business. What is most important is that you feel comfortable enough. Now that I am out, I actually feel LESS comfortable using the men's room, because I am still fighting feelings of being "fake" and not belonging there. (Where before I just didn't give a crap whether I belonged or not, I would do as I pleased, lol.) So sometimes I use the men's and other times I use the women's. I wouldn't worry about women calling you out until you start growing facial hair, though. Until then I bet they give you the benefit of the doubt (unless you're lucky enough to be, like, six feet tall and built like a linebacker).
