I have seen a lo of questions on Facebook on when if and how do you tell your child thy are autistic. Answers range from don't tell them to sit down and have a long talk. There is no right or wrong way to approach the subject. Every person is different. Except the don't tell them that is the best way to make your child think there is something wrong with them by hiding things from them.
I have mentioned before that we never had a big sit down talk with Roger or Lucy about their autism. It was just more of a known fact around here. We never left the room or talked in hushed tones about it. Whatever needed to be said would be said regardless of who was there. Talking in hushed tones just makes the child feel like there is something wrong with them.
Roger was dx at age 11. Lucy at age 7 (though suspected since age 2) I had a couple of books about autism on he table he saw them and asked so this is the brain thing I have. Yep was my response and that was the end of that. No drawn out yes but you need to know there's nothing wrong with you etc. Just straight forward answers. He doesn't want a lot of drawn out info he wants facts. Lucy I don't think anyone has ever directly said you are autistic she just knows.
Both kids have read the books that they are interested in. If they have a question we answer it. For us there was no need to stress out over telling them because well it was a known fact in the house. They have always been present at Dr. appointments so they hear everything. They are never asked to leave. They play a active role in any therapy which led to the decision to stop all therapy. Roger has been present and a active voice at every IEP meeting starting in middle school.
So while you are thinking that telling your child is going to be this great life changing moment. That you may hurt them. Really they already know (you think your hiding your talks your not) and by bringing them into the inner circle and having them actively participate to their abilities only empowers them.