I just got perscribed birth control today by my doctor.. I'm 18, and I'm using it for terrible cramps before and during my period. Also because I'm sexually active.
Anyway, the problem is that my doctor didn't tell me when I should start taking the pill.
I read the packet that the pharmacy put in the bag and it said to take it on the first day of my period.
However, the packet that was in the pill's box said in one part I should start the first day of my period, and in another part said I should talk to my doctor about when a good time to start is..
Should I really call my doctor and ask? Or should I just take it on the first day of my period.

Yeah, call your doctor. If they aren't available you could also ask your pharmacist.

Okay, thanks.

And you do know it is not effective from day one, right

Oh yes, I know. I'm not going to have unprotected sex. I just wanted it just in case the condom breaks, so there's a less chance of getting pregnant.