Help?

On Thursday night the 23rd, I had unprotected sex with my boyfriend of 7+ years. It is now the 25th. I was gonna go yesterday to buy the morning after pill but because of work I was unable to but was planning on going today. However, I woke up feeling cramping and you know that feeling you're used to getting before you get your period, when you just "know"?. And when I checked my eve app, since I have it up to date, it asked me if I got my period today meaning I'm supposed to start it today or tonight if not tomorrow. I don't know if I should wait till tomorrow to see if I get my period tonight, or if I should just go and buy the morning after pill now. I have no problem buying it, but I just don't know if it's okay to wait till tomorrow, or just take it now. And IF I do get my period tonight, does that mean I'm safe? Like to not worry?