Sex is FUN
Sex is the best. In a world full of so much chaos and violence, sex is one of those rare and natural pleasures that we all deserve to have without repercussions. Orgasms should be had on a daily basis by everyone. Maybe that would inspire world peace.
Just because it's the first date doesn't mean the sex won't still be a really good time. If it feels right, go for it.
If he or she doesn't call, that person isn't someone you want to date anyway.
Let's be real, the main reason you're not banging someone on the first date is that you're afraid of being slut-shamed and not getting a second date. If you go on a really great date, fuck that person. If they don't call, that says a lot more about that person than it does about you.