Birth Control and Cum

So I’ve heard that some people allow their boyfriends to cum in them while they’re on birth control. Ive also heard that there’s a certain amount of time that you should allow the birth control to start working. I’ve heard that I’m pretty much safe after 7 days and I’ve heard that you should wait 1-2 months.

My boyfriend and I have been anxious to try but too scared to actually do it.

Thoughts?