Need advice!

My SO and I had unprotected sex this past Saturday and he used the withdrawal method and came in my mouth. This was the first time we have ever done it and I'm extremely paranoid of pregnancy. He keeps advising me that he pulled out in time and that'll it be ok, but there's always the scare of precum and what not. It was 5 days after my ovulation ended and I'm suppose to start my period in 6 days. Should I take a pregnancy test or jump straight to Plan B? Today is the 2nd day after unprotected sex and I'm afraid the pill might not be effective with it being so much later. I'm aware I made a mistake, I'm aware of the consequences, and I'm aware that I shouldn't be doing things if I'm well aware of it. It was an accident and I really need a form of advice or a second opinion. I'm trying not to stress too much but it's kind of hard. Please help!