Hello doctor, I had sex 6-7 days before my period, I bought daily birth control pills but the pharmacist told me to take them after my period... I still haven't had my period, I'm so worried, doctor, please advise me!

I just finished the first pack of my last cycle. So how long do I have to stop before I can start taking the second pack of my birth control pills? Since it's the first time I've used it, I still don't understand it. Please guide me, thank you.