Depends on your cycle length. Take your average cycle length, subract 14 days, and your fertile window starts a couple of days before that. For example if you have a 30 day cycle, 14 days before that would put you at cycle day 16, that's when you most likely ovulate. Your fertile about 5 days before ovulation day and the day of ovulation. so count the first day of full flow as cycle day 1 and go from there. Good luck!
August 01, 2008