Just for an easy answer, my rule has been:

• Online - I'll just put it on the profile, but I'm not using a service that expects me to list myself as trans because I'm really not interested in people who were specifically searching for that. Short paragraph at the end of the profile, weeds out anyone who it would be a complete dealbreaker for but gives me a fair shot in the sense that they at least have to learn a little more about me the person first.

• In Person - Second date. I'm not saying a thing on the first because my safety means more than some guy getting a little grossed out. I at least need a little time to make sure they aren't crazy. But it is something that should be brought up early, partially for safety reasons and partially because it would just be more heartbreaking for it to muck up a months/years long relationship.

Also same thing about getting to know me first, I'd imagine the group of men who absolutely would not date a transwoman is smaller than the group who think they wouldn't hypothetically but have never been in a scenario where it's someone they know they are attracted to otherwise.