... that I was pregnant. I know for sure that the only time that I could have gotten pregnant is on Saturday or Sunday. The pill says to take within 72 hours, which I did. Since, I am constantly worried, I went to the health center at my school today and it said that I was positive too. However, prior I was researching online and it said that a sperm would not reach an egg until 72 hours. I was supposed to start my period late Monday afternoon. What should I do? Go and buy another pill of Next Choice?