I don't think 25+ is considered a late transition. I'd say it's a borderline young/mid-transition. I'll be starting soon probably. I'll be 26. I still feel young and physically could pass for 20 easily. I could probably tell someone I was 17 and they'd likely believe me. I knew kids in high school who looked older at the time, more so then I do now.
I really don't have any friends anymore, so that went easily I guess. My family? They've been OK, but I feel like it's just like "Oh well" with them. My mother said to me a few days ago that "I guess I lost my son" and that was pretty hard for me to hear. My family are good people, no one would disown me, but I still feel bad about killing my mothers son. I have a lot of female cousins, all like 17-20, one a few months older than myself, and a 29 yo sister. My younger cousins are ultra-fem and sort of stuck up. I haven't seen anyone since coming out. My mother sort of outed me. I'm kind of worried about what their reactions will be, knowing that their only guy cousin might be becoming a woman. I was in a psych hospital for depression a couple months back, one of my uncles tried to call a few times ad then wanted to bring me to a baseball game when I got out, after finding out I was trans. I've avoided him, but I appreciate it and will probably write him a nice letter. Him and his wife spend their time in FL during the winter, so I'll hopefully take him up on the offer then.
I'm worried about how people will treat me during and after transition though. I'm sort of hoping that my younger female cousins become horribly interested in me and we can become closer, but I don't know...