I thought this article from AmericanTransMan was an important article to share. I too have had people out me without them realising this is something they should have asked me about first, hence I now always make a point of telling people “it’s not that it’s a big secret, but please use your common sense and discretion as to whom you tell, and don’t do so unless you deem there to be a very good reason.”
For me personally, that’s more a case that I don’t want my “transness” to precede me. It’s really not the most interesting thing about me, and though it’s a physical fact, it’s simply not how I identify.
Having said that, everyone that’s close to me, knows my story as I find it pretty much impossible to really get to know someone unless they know this about me, as it does require a great deal of censorship and any aware person can tell I’m with holding something from them after some time. After all, it makes up a huge part of my life story, world view and social conditioning, but I prefer to be the one to tell people and not leave it up to others.