Personally, I wouldn’t sleep with someone on the first date, but if it was a casual thing then that would be okay. If I’m dating someone though, I like to take time to get to know them before having sex because it can be an intimate experience and I don’t want to share that with just anyone.
I think it’s important to acknowledge that everyone experiences sexual desire differently, and as previously mentioned some people might not consider sex an important part of a relationship (hello asexuality)! So I think with asking questions like this, particularly with friends, it’s important to take that into consideration (that maybe not everyone feels the same what that you do about sex).