pregnancy

I took a pregnancy test Thursday which is just a little bit past a week after I had unprotected sex and it resulted negative. Knowing that tests the first time can result negative even though you may be pregnant I'm trying to figure out when to take another test to get more accurate results. Today is Saturday and I typically start my period in the first week or 2 of the month. is it safe to take a test again today or should I wait a little bit more? I need another opinion that isn't mine.