We're also very open about topics in our house. We haven't started using the "GT" phrase at this point though. We have taken an similar approach with "different kids are ready for school at different ages." DS also knew something was up when he was getting tested this summer. He's no dummy (duh!) but we positioned it as we were meeting with the doctor to make sure that we were meeting his educational needs.
But we wait for situations that come up. We don't just bring it up for the sake of talking about it. For example, we know he's a little bored at school and when talking to him about being bored at school we'll use it as an opportunity to explain to him that people learn at different speeds, etc.
JB
