I want him to cum inside me

So my bf and I have been together for a year and we’re very careful when we have sex. He really wants to cum inside me and I really want it too but we’re both scared that I might get pregnant.

I’ve never had a man cum inside me before and I really want to try it just once! When is the safest time to try it without worrying about getting pregnant?

Edit: I’m in a country that doesn’t give birth control/IUD unless you’re married 💃🏽