What is the best time to have sex for conception to take place?

In the few days before ovulation. The tricky part is knowing when that is. A good starting place is about 12-16 days before the next period is due, and then watch for possible changes that may show ovulation is occurring a bit before or after this time... which is normal for many women. Trying a few days sooner and continuing a few days later may be wise.

Some couples will have sex frequently throughout the cycle and then a bit more often about the time they think ovulation may be coming up and a couple of days afterwards.