Late period

So I was supposed to start my period today. Usually my period is on time since I take birth control. On the 21 I totally forgot to take my pill because my boyfriend took me to the Brantley Gilbert concert and I take it at 8pm so I was going to take it when we got home but I totally forgot. We had sex that day and the day after and I forgot to take the pill on the 22 as well. I'm nervousness about this whole thing. Please help. When should I take a pregnancy test?