Hard to say exactly, but my husband & I had sex on the 1st day of ovulation & we're expecting our son any day. Position also plays into it too. I read up on what positions are more likely to create boys. Basically you're man needs to be as deep as possible because the male producing sperms are lazy swimmers & don't seem to live as long as the female producing sperm. Surprise, surprise! LOL!
They're really isn't any in what I've learned as a nurse. The sex is determined by the father- the ovulation cycle plays no part in determining gender.