IMHO the disability conversation can be like the conversation for an adopted child; you want to make it not a big reveal, but something he later feels he's always known about himself, like brown eyes. We thought we would wait until DS could handle the news; but at 8 he had already intuited that he was a terrible person for not behaving like other people, and so much damage was done by our not getting out in front of that. He is still coming to terms with his disability, but he knows a lot about it, and that's been useful for him in thinking about himself.

So: just a thought.
DeeDee