Edit: to clarify, my question is more about when (before 2nd date or during) and how should I tell him.

Hello! I recently went on a first date with a guy, and the chemistry was great, and the date was lovely. We have a second one coming up. I am sexually abstinent (waiting till I am married) and was planning to tell him during our second date. My thought process was if he cannot wait, we are incompatible and/or he was looking for something casual. Is this a good or bad idea?

It seemed like he wanted to sleep with me on the first date so figured it would be a good way to vet and know for sure whether he is looking for casual dating. Didn’t occur to tell him on the first date unfortunately...Perhaps I should tell him via text/phone call (texting would probably not be tactful right?) or over coffee briefly before then to avoid wasting both our times? I am pretty sure he will reject me when I tell him so not sure if there is any reason to spend a few hours with him just to fall for him more.

Would appreciate your thoughts! Thank you!