Period/BC Wonders

Lauryn

So I have a question for anyone out there who may be able to help! I started a birth control pill on September 3rd! This is the first BC I've ever been on. My doctor told me to do a Sunday start after my next period had started. The four sugar pills are the last 4 pills in this pack. This app says my next period will start on the 24th/25th, but the brown pills begin on the 27th. I guess my question is, when do I need to be expecting to start? I don't wanna waste a bunch of pads if I don't have to while trying to figure out when it's coming