Got Mirena IUD, had unprotected sex hours after

Hi, I just got the Mirena IUD today!! I’m very excited about it. My boyfriend was over a few hours later, we had sex, and he finished inside of me.

I thought it’s one of the best forms of contraception, so we’d be fine, but I just read online you’re supposed to wait 7 days after insertion to have unprotected sex?? The midwife who inserted mine didn’t mention that, so I was wondering if that’s true? I’ve also heard it works immediately upon insertion, so I don’t know which is correct.

Or does anyone have experience with this-if you had sex the day of insertion, any pregnancy scares?

* Update: I called the office and spoke with the nurse who helped with my IUD procedure, and she said it was effective as soon as it was placed in!