Just wanted to chime in here. This is a really good question/discussion.

I suppose for us, we wouldn't need to tell DC definitely until much later and only if there was a reason to.

DC already knows there is a difference, that can't be helped.

I consider that later, it is useful for DC to know that there is a difference, that the other kids can't help being who they are, and that is just how things are. I like what some of the others have said about not stressing on the test because it really is just one number, one test, one day. More important is who the child is, as a person, with a gift, but to do their best, and be understanding of all people.

Also, that because of the difference, there is nothing wrong with DC. "You are normal amongst kids in this range."

I think, I would never actually say the number, because it is misleading. However, I will tell DC about the giftedness, the intensities especially, and understanding one's own perfectionism issues.