Birth control

I know this isnt posted in the right section but ive already posted twice in 'birth control' and im still not getting a clear answer and cant find anything else on the internet..soo im hoping ANYONE can help me...so im starting birth control for the first time and my pack says start the sunday following your period. If i got my period today (Sat) do i start the pill tomorrow (Sun) or wait til next Sunday after my period is over?