My first time taking birth control

Sara
So I got my pack yesterday and I am very confused. Its a 28 day pack that starts with Sunday. It says to take it the day you get your period. However, what happens if I don't start my period on Sunday, do I wait till Sunday to still take it our take it the day I got it but what would happen to the other pills? The instructions come with a sticker schedule what do I do with that?