Day of missed period - should I take a test 7 days after conception ?

So today I am suppose to have my period. Last Monday, I had unprotected sex, pulled out but  believe no ejaculation was inside of me. According to my calendar(26 day cycle) I ovulated two weeks ago and had sex a week before my period. I took plan B about 22 hours after conception. I would like to take a test but I believe it might be too early since its been 7 days since my conception, but I know people say to take a test the day of your missed period. I know plan B delays my period, if I take a test should I relay on the results?