most women ovulate 14 days before the onset of their next period so on a 28 day cycle it would be day 14 and on a 33 day cycle it would be day 19. To be safe you could BD every or every other day during that time period. Using ovulation predictor sticks will really help narrow it down though, as well as bbt monitoring.
You have to chart it to be certain. It can fluctuate from month to month. It should be about 14 days, but can vary. So, you can buy an ovulation predictor kit, take your bbt (body temperature) every morning, and check for changes in your vaginal discharge. That is the only way. I have enough symptoms that I can tell when I am ovulating. Sometimes I can actually feel it. Good luck.
last period was oct 11 2007 not nov...oooopppps lol