1 Start your pills today. 2  If you start your pills today, you should use a backup method of birth control (condoms with spermicide) during the first 7 days of the pill package. 3  Birth control pills will start to protect you from pregnancy after the first week, if you take them correctly. Use a backup method of birth control (such as condoms with spermicide) until you start the pill. 2  The pill will start working right away for birth control if you start on the first day of your period. 3  Start your first pack of pills on the Sunday after you start your menstrual period.