On the off chance our timeline isn't synced with theirs, we should think about responding sooner rather than later. If it sits all weekend, fine. If not, we know that we aren't running fully aligned with their time stream and don't miss an opportunity to connect. I imagine it's safe to assume, but we all know about assumptions.
And as curious as we are about the past, we are doing this to help them. So perhaps we keep the body of the message geared toward assisting them, and then tack on small questions he may be able to answer as a post script.
Just a suggestion.