See, I don't see as 'not telling' as hiding myself. I am being me, and if it's not apparent I'm trans, then I'll say it when necessary, not because it's some kind of secret that has to be revealed, but simply for the sake of honesty - if I spent years with a guy and he found out, he may well be cool with the idea, but may be more angry by the fact that I felt I couldn't open up to him about it. I treat it the same as if I was born with AIS, or I had a hysterectomy, if I was sexually abused, if I was infertile, I grew up in a house full of men, or whatever. All of these things may affect my body or my gender identity in similar ways in comparison to being trans - but would you reveal these things on a first date, or first encounter? Probably not. It's simply part of my life experience. Rejection or breakups can happen at any stage of the relationship for any number of reasons, so being upfront about being trans doesn't necessarily prevent you from getting hurt in the long run for any other reason. I still agree with it being mentioned relatively early on, but not necessarily on the first encounter - for me, I just don't feel the need to bring it up, I'm just me, trying to get to know somebody and having fun.
I have used this approach and no potential date has ever had a problem. In one guy's words - "you're still you, it doesn't change anything" - and he only said that because he had got to know and like me in the first place. If anything, the more likely reason for rejection is probably if he wants to have his own genetic children and have his future wife bear a child 'naturally'.
