Idk how you handle it in real life. I don't tell anyone unless I'm expecting to be dating them since then they would need to know about my genitals (for obvious reasons). None of my friends know I'm trans (except for my best friend who knew me since before I transitioned), even though they're almost all lgbt+ and all are "trans-friendly". I just feel more comfortable this way.

So if it's important to you that your friends know that about your body and you don't want to be stealth, you should tell them at some point because I assume that it's pretty uncomfortable when you want them to know but don't know how to tell them.

But always remember that you don't have to tell everyone you're trans. Transphobes might disagree, but you're not lying if you simply don't want people to know about a part of you past and your body. Just like how guys with micro-penises don't go around and tell all their friends about it, you know what i'm saying?

However, if you want to tell him because you want to see if he's supportive of trans people there are other ways. Don't come out if you're not ready. Take your time, do what feels right and if he doesn't accept you it's his loss.