TTC Babyboy

Hi everyone. I have got two girls and now ttc a boy. So its said that for babyboy , u DD on the day of ovulation or day after. But my silly worry is, egg only survives 12-24 hrs after release right so wont I miss the egg and egg disintegrates if I DD the next day after ovulation ? Also, the opk strips that we use, shows LH surge only. Which means we are yet to ovulate if the LH is two strips is positive. Does that mean for babyboy, if the opk is very positive, then I DD only next day ?? Or 2 days later ? Pls help!