After how long does birth control take effect?

Mariana

Hi all! So I recently started taking birth control, and this is my first time ever taking it. The pharmacist told me that for the first 7 days of taking the pills I would need to use another form of contraception and that after that I should be okay if I don't use another form. My issue is that I have also heard from people that it takes a month. Does it depend on the pill brand or something? I'm confused!