Birth control

Hey guys I was just wondering if anyone could fill me in with some information.. Yesterday (Sunday, May 15th) I started my birth control for the first time ever. (I am taking Alesse 28) I was on the 5th day of my period & there was really no blood, there was only a little bit of brown when I wiped but that's it, so I was just wondering how long until the pill is effective, thank you!:)