I think expressing your firm desire not to discuss it 'on the spot' is right on. But do ask your child in advance the 'friend v. big kid question' in advance, and explain that you believe that he can make friends anywhere he goes if he acts friendly. Your son may get the vibe that the principle 'wants' him to say that he'll miss his agemates, so it might be wise to state this before hand, that what most kids are concerned with is making friends, not learning, so that most adults are worried about this. You can say that you believe that he needs BOTH a chance to learn and friends.
Your son will also have picked up on your excitement/nervousness by now, so you may want to figure out how to acknowledge this without tipping your whole hand. "I am remembering how nervous I was when I first visited school." may cover it.
I'll be praying for you!
Grinity
