HELPPPP plan b?? Is it too late or should I still take it?

I had sex 2 days ago and my period was supposed to come the day after I had sex but it hasn’t it was my first time idk if I should take plan b? Or keep on waiting?? It was un protected for a few moments but then we put on a condom! so like I’m still scared about pre cum or what I should do plsss HELPPP I’m trying to stay calm lol