Telling my folks was, without a doubt, one of the hardest things I've ever done (and I was 27!). It was awkward to discuss (couldn't bring myself to say the word "penis" in front of em'...lol - just kept calling it "my member"), and it took a good
chunk a' time to explain the surgical options that I was pondering (at hearing that some doc would potentially be shoving plastic and such into my nether-regions, they actually (laughingly) suggested that I first try to better explore sex and dating while impotent!!). But in the end, at hearing how lonely and depressed the impotence had made me, and on hearing how much research and such I was doing into other/all treatments, they ultimately came around...hell, who do you think's driving me to the hospital in a couple weeks?
Now all that said however, my ultimate advice is that the choice depends on you and the relationship you have with your folks. If you're close, and feel that they'd be supportive and understanding (and again, I'm sure
they will be), then hell yah - tell em' ASAP! IMHO, the notion of verbalizing troubling issues in one's life (especially one as maddening and life-dominating as ED) can't be minimized. Trust me from experience, once everything's out there and off your chest, you're gonna feel a whole
lot better. Moreover, as Magic perfectly said, remember that we're fighting a medical condition; nothing
that's happening to you (or "not" happening I suppose) is your doing - it's just a (more than likely) random birth defect - no different than being born with a bad toe or cross-eyed or whatever. Approach it like that - as a clinical, medical issue that can be analyzed and treated - and not
as some judgement of you or your potential as a man - and making decisions will get a whole bunch easier.