can you get pregnant if you just started birth control?

I had sex with my boyfriend in New Years and I'm new to birth control and I was on my fourth or fifth day of taking it and we had unprotected sex and he .. did a few times... could I still get pregnant? Because I read that you should wait a week when starting birth control before you have unprotected sex .. because it could be possible.. and i was ovulating this week... has this happened to anyone and you go pregnant ?? I've been thinking a lot about it I'm kinda worried 🤔