Is it smart to have sex while fertile?

I plan on having sex tomorrow since I’m going to be in my boyfriends house. Anyways tomorrow It’ll be the 3rd day of my fertile window.

It says I have a 15% chance of pregnancy but we are definitely going to use a condom and I have a plan b pill ready to go. Is it okay for me to go ahead and have sex? I really want to and I don’t know when we are gonna have this opportunity again.

But i just wanna be completely safe.