Shettles Method and opk

So I’m gonna try the Shettles method (google it) and using opks. I’d like to try for a boy ( either is awesome tho ) So if I get a positive on the opk that means I’ll ovulate 24/48 hours correct ? And the conceive a boy it says to BD the day of ovulation. So I’m thinking if I get a positive on opk I’ll BD the next day and day afterward. But what if I ovulate before I get to BD. How long does my egg hang out ? 😂