Timing periods

I'm currently preTTC, but want to get started as soon as possible with my husband when we are together again in late March (we're currently apart). 
I'm on the pill and try to have as few periods as possible because I have heard that is a way to extend your fertility. 
I need help working out the timing of stopping the pill so that I will be fertile in late March when we're back together. I'm bad with numbers and can't figure out how to do it without having 2 periods. I think my cycle is about 31 days when I'm not on the pill.  Assistance gratefully received!