Taking my birth control correctly,i was told to start them the sunday after my period but instead i started taking them the next sunday ? will that have any affect on the effectiveness ?my period is scheduled 2nd week instead of 4th,what should i do?

Less effective but: The reason to start when a period starts is so that you know you are not pregnant at the start. If a teen is not having sex and is using pills for other medical reasons, when she starts does not matter. Teens do not need to have sex. If she is having sex, but started pills late as in this case, she should continue the pills but also add condoms this month. Her "period" comes on the inactive pills.