Tell those who need to know because it will affect their interactions with him - teachers, etc., or if your child's behavior is such that it needs some explaining. I know this flies in the face of the recommendations to tell no one, but I've learned with my own 2E son that understanding by others has made all the difference in their interactions with him. It also has helped him not be ashamed of his differences. He tells classmates he has dysgraphia when they make fun of his terrible drawings or writing, and it changes the way his classmates interact. They accept his quirks better than if they didn't know.
I it isn't the kind of thing I tell strangers, but I don't hide it, either. It isn't something to be ashamed of, and if kids get the idea that you're hiding it from others, they'll innately think it is something they should hide and be ashamed of. Undoing that is almost impossible.
