Plan B

I recently had sex with my partner about 12 hours ago and as luck had it, he did not pull out. We had had sex about three times before this time back to back and he came all three times but pulled out. He said the fourth time nothing really came out because he was already spent from the previous rounds. I plan on taking a plan B within a few hours and was wondering how would it affect me if I was already supposed to have my period in a few days? I’ve been cramping and showing symptoms of my cycle coming on, so if I take this plan b , my period should come next month correct? 🤦🏾‍♀️