When do I take the pill????

About 2 to 3 months ago I was on the pill secretly as my very religious parents would think it was just for sexual purposes but it was to help out with my breakouts. It helped but I eventually had to stop using it because my mum would be hovering over me and asking questions about why I had this alarm go off everyday at the same time. Ever since I stopped I haven't had a period and now I need to start back up again because I'm seeing my long distance boyfriend of 2.5 years in 3 weeks and we are going to lose our virginities together and usually they tell you to start the pill the first day of your period! I know I will most likely need to use a back up source of birth control like condoms but please help a girl out!