Good age to start the process. But he has to have some sort of disorder that the adult child is unable to make certain decisions himself. Not that he won't, but that he can't, I believe. I think we also had a lawyer appointed. My son is on the autism spectrum and does need some help.
I've been considering this, as well. My son is highly functioning but I fear for him just to remember taking his medications, for example.
Don't know how hard the School of Hard Knocks will really be ...