There isnt really a standard answer to your question.....I find it best to use OPK (ovulation prediction tests) they are like Preg tests but they test the levels of Luteinising Hormone in your urine. When the OPK goes positive then you will generally ovulate within 12-36 hours. The egg stays viable for about 24 hrs then if not fertilised you will get your AF in due course. Hope that helps a little.
A `normal' cycle is supposedly 28 days with ovulation occurring on Day 14 of your cycle but many many women do not have a cycle like this.
I wasn't sure if I was ovulating at all so I started charting (taking temp each morning). This is a bit of a pain, but a sure fire way to know exactly when (or if) you did ovulate that month.
BDing is best 5 days prior to ov, the day of ov and the day after as well.
GL