Birth control confusion🙄😩

Karla
Help a sister out guys! I just got my birth control pills today, I've never used birth control before and I'm really confused on when I can start taking them. I'm suppose to get my period Monday, but I keep seeing different things like start the Sunday you start your period, start the sunday after your period, or start whenever. Boyfriend is deployed & comes home next week so I really need some help!