Shoud the Plan B work?

I just had sex and took the pill 20 minutes later, it was the generic one Take Action. It was unprotected sex and I told him to get off because I got scared so he did not finish at all and I am aware or precum. According to my period calander, today it says fertility window high and the fertility window started the the 8th as low fertility window and ends the 14th, my ovulation date is the 13th, sunday. My period is expected the 27th its pretty regularly every 28-30 days. Should the pill work?? And will my period be as expected??