Due to my OH's low sex drive, we mostly only did it on the day of the +ve OPK - nine cycles later and I still wasn't pregnant. For the past two cycles we've been taking a NTNP approach and have actually been having sex a bit more.
The ovulation test adverts say the tests can tell you the two best days to BD on, and it makes sense that the closest to ovulation you have sex, the more likely you are for the sperm to reach the egg. Personally, I think there's too much focus on +OPKs and not enough on observing fertile CM.
I read a study a while ago that concluded there was a better chance of conceiving if you had sex during times of fertile CM, despite proximity to ovulation.
It makes sense to me as having fertile CM really helps the sperm to get to where they need to be and to survive their journey.
Personally, by the time I get my positive OPK, my CM has pretty much dried up and my cervix no longer seems 'favourable'. So for me at least, I think it's more important to have sex on the days leading up to the +OPK.
Went off on one there a bit, sorry!
Of course, there's plenty of stories of ladies that did it close to ovulation and got pregnant.
So if you really do want a boy and you're not feeling desperate to conceive, trying to aim for as close to ovulation as posible seems like a good idea, it's still very possible.