Like JoyRenee said, every woman can ovulate at different times. I looked into knowing when and what to look for when I was ovulating. I have a 29 day cycle right on the button and just counted back 16 days from when af was due (2/2) which I would've ovulated around the 17-21 of Jan. Dh and I bd on the 16 and 18 and I am now pregnant. Maybe we got lucky, I'm not sure but you have to look for the signs of cm and might experience slight cramping too during ovulations.
Best of luck in ttc.
Okay, here is some Health Class 101!
A woman does NOT always ovulate on CD14. That is such a common misconception and why women have a hard time TTC! And exactly for the reason you just stated. If you ovulate on CD12 but you're going based off numbers and have sex on CD14, you MISSED the egg (it only lives for about 24 hours).
What happens is women believe they ovulate based on their last period---14 days after a period. That is NOT true. You will have your NEXT period based on when you ovulated, so it is the OPPOSITE thinking. You will get a period within 12-16 days after ovulating, known as the luteal phase.
As for how many days you have to get pregnant, there is only about a 24-hour window of time that the egg can be fertilized. Doctors advise you to have sex the day BEFORE and the day AFTER ovulation. Sperm can live up to 5 days in the vagina. Most women just have sex every other day during their fertile time. Having sex after your ovulation time may "catch" the egg in its final stages of dying off, but you're more likely to become pregnant if you have sex before and during ovulation.
Other ways to know when you ovulate: cervical discharge/mucous (CM) which looks like raw egg whites, BBT charting, OPKs (I don't know about the last two, but if you need help in the CM dept. just ask me!).
Anyway, hope that was more clear to you. Read over it a few times and visualize what I'm saying. That kind of helps!