In those cases, I usually just wait a couple days now, then give a simple response. In your case it might be something like, "Cool. I will have to check it out once it opens." Or something else that validates his excitement and anticipation.
You aren't "waiting on his conversation", but you aren't denying he contacted you (or worse), either. Something my W does to me all the time, by not responding.
Consider what could have happened had I ignored my W last Thursday. I may have missed an opportunity to have my D8 this weekend. I can't thank my friend enough for convincing me to respond. And had I jumped at the chance to talk to my W, could have ruined my whole evening.
I'd say you're within the statutes of limitations to still respond back without looking desperate for that time of interaction with your H, and still appearing sincere in acknowledging his existence and excitement. And then... be consistent with future dialogues...
