I had sex yesterday, used a condom and bc. started my period feb 10th. got the depo-provera shot feb 25th. is the depo-provera already effective and working now?

Birth Control Switch: Technically, the Depo-Provera shot has been shown to be active fairly quickly, thickening the cervical mucous and making it impenetrable to sperm (within a day even). However the general guidance is that after getting depo, you should continue birth control pills and/or condoms for at least 7 days before being sure that you can rely on the depo.