Depo shot

Samantha • YouTube Vlogger | mommy of 2 | engaged to be married !
Hey girls , 
I just recently had my baby boy on July 20th , I started depo September first . I'm not sure if I want to continue with the shot , I haven't had any side effects so far . I've been bleeding for 3 days now , light period ( thank god .) I'm just scared of getting all the bad stuff later . My question is , how long after your shot is due do you have to wait to start taking the pill instead ?