birth control help pleasee

Hi! So in 2 weeks my bf and i will be together and may have sex. Ive been on bc to regulate periods and stopped in june. I picked up a perscription today the pharmacist said to wait until next month to start. I called another and he said start tomorrow on sunday. Well i will use condoms too but want the bc to be effective. I know it takes 7 days to kick in. Does anyone know if i start tonight and take it the same time will it be effective enough??? Im just so confused at what to do!!! Im just paranoid since ive heard of people who dont correctly use the condom right the first time and we were gonna pull out too. Any help!!! I may just buy plan b to have to ease my nerves.