Suggest Methods To Relieve Cramps During Menstruation

I recieved a Low-Ogestrel birth control perscription today, and it says to start taking it the first day I start my period. I am not taking birth control for protection, I am taking it to relieve heavy cramps and vomiting on the first day of menstration. Would it be a health risk to take the wednesday pill tonight and start now, instead of taking the pill on the first day I start?