>> I replied, "Your Honor, when did you know you were a boy?" <<

SCORE! Great way to answer the question in such an empathetic way.

>> I think since cisgender people (of which I am one) so rarely question their gender identity, they don't realize how early they KNEW it. <<

So true, especially about the questioning part. It often isn't until someone's assumptions about gender identity are challenged by a person they care about that a person becomes open to looking at those assumptions.