imnotaboy
Firstly, this isn't the sort of place where you get shoved around to irrelevant topics. Most of us here are trying to understand ourselves and each other. I'm pretty sure we all love looking at new questions.
I was in a similar position to your friend, though, probably more like you, I knew what I am.
To be honest, since your friend has this confusion, what he (assuming a he), probably needs to do is just take some time.
It isn't a race.
OK, it's better to start early, speaking as a 55 year old who still has a load of excuses for delay. But equally, it's silly to the point of insanity to start something you don't want to do.
Getting over the issues and hangups of his upbringing is his first hurdle.
As his friend, may I suggest you let him talk when he wants to, but otherwise, don't press the issue.
Hopefully, he can have a nose around here. There's a load of information. The Wiki is especially good.
And since you asked us not to mention when we first realised, I was 4.

Best of luck and great to see you.