I did it.
I had THE TALK with Jedi Knight.
Two different events in the last week convinced me that it was time, and finally after months of thought and prayer (really, I'm pretty uptight when it comes to finding JUST THE RIGHT WORDS), the exact words and approach I needed finally came.
Ideally, I would have naturally answered questions as they arose, but there weren't enough questions asked in proportion to what he needed to know.
It was great. Uplifting. Science, spirit and love-based. He came away with a hug and smile, and the knowledge that he can ask his mother about anything. Piece of cake.
Onto the next major challenge.