If you have an hour to listen to this in the background, this is worth your time. Kim Pearson talks about having a transgender child who transitioned before age 18, and about TransYouth Family Allies (TYFA).
A quote from Kim Pearson, the president of TYFA, on transitioning 5-year-olds (from about halfway through the audio piece):
The biggest concern people have — and even some of the “experts” … — but the experts will say that there are risks involved in letting a child that young transition. And, my answer to that is that there are equal risks involved in not letting a child that young transition.
I’ve always raised my kids under the guideline of “What’s the worst case scenario? What’s the worst thing that could happen?” The worst thing that could happen with transitioning a 5-year-old — a miserable, suicidal 5-year-old — transitioning them, and the question is “What if they change their minds?”
And my answer is “What if they do?”
You haven’t really changed anything except their hairstyle and their clothes and the name that you call them and the pronouns. So, if they change their mind, you change it back. It’ll be uncomfortable; it’ll be embarrassing — but you know what? That’s more about you — the parent — than about the child. And, what have you done for that child except send tell them — you’ve sent a very strong message — I love you NO MATTER WHAT.
So, you’ve kept their self esteem intact.