Is there a reason why they would find out later? If not, ask yourself, why do they have to know? In a non intimate relationship, what you do or don't have isn't going to effect the friendship. I do think that if after a few dates, you think it might get serious, then there is a need to know. By waiting to tell, they have a chance to get to know you as a woman, and by the time you tell them, they are thinking of you you as a woman, not a transgender.
There is a fine line between when to tell someone. You don't want to get so emotionally invested in the relationship that it would kill you if they couldn't handle the truth. Telling them right away though, gives them no chance to ever see you as a woman first and a transgender second. For some people, that is just too much.
Telling someone is a very personal decision. Some would consider not telling all their friends a betrayal by omission, while others feel that there is no reason to tell them. If you are considering dating the person later on, the you will have to tell them at some point. The more people you tell, the more likely it is that you will be outed before you are ready. Lets face it, for a large portion of society, transgenders are good gossip and not something people see every day (actually they may and just don't know it).
Follow your heart and your morals.
sam1234
