So my advice would be: It really just doesn't matter. Like, seriously. If you want to date someone, just do it. When your parents see it, just tell them that you're gay or trans or whatever and act like they're already supposed to know, that you're surprised that they don't, and that it's not a big deal. Otherwise, coming out is just pointless, and causes you a lot of stress.
Perhaps I'm just jaded after all that though. =/ I feel bad for saying that, because I don't want to scare people off, and make them think telling other people is a bad thing. What's important is that you just do what you want. No one else matters, and their opinions matter even less. (Unless we're talking about religious parents who could hurt/abandon you... in which case, it's probably best to just wait until you're on your own, or have a LOT of backup before they find out.)