When will Orlifique start working if I start using the pills on an unspecified day of the cycle?

Good morning, I have a question about birth control pills. I have very irregular periods (occur every 3/5/6 months). My gynecologist told me to start taking the pills without waiting for the first day of my period but right away. My question is when will contraception in this case start working? With the start of the second package? The pills I take are Orlifique