When I was 18, back in 1999, I first went to my GP who knew nothing of the condition and sent me to a gay men's support group, and went to my first private gender clinic. I'm now 36 and only now am I out and properly transitioning. Had I kept on it when I was 18, I'd have probably been post op in my early 20s, spent my university days in my preferred gender, started a career in my acquired gender (and thus able to be effectively stealth at work, with a full employment history as a female).
But I regret none of it. Had I transitioned I wouldn't have my daughter who is the most amazing person ever. My family are all now supportive, but I don't think they would have been had I come out in the late 90s. Times are very different now. I've had great experiences, and I've been able to build a good career. And as much as I might have this daydream fairy tail of how amazing transition for me at 18 would have been, equally, it might not have worked. I might have been distracted from my studies with transitioning in a different time, might not have made the career that I did. I'm no believer in fate, but for me, I just believe that I transitioned at the right time for me