Mating happens during waking hours. Quite often, a rooster is very amorous first thing in the morning and will mount most of the hens. This depends on how many hens there are, and how much the rooster likes each of them. A rooster can mate a single hen several times a day, or if there are more hens he may mate each hen every 2-4 days. Younger roosters are more active,
my older guy is more settled and not so demanding anymore.
A hen stores the sperm internally for around 2 weeks from a single mating. So, she can lay fertile eggs that long (and even longer, possibly).
If I have a rooster in my flock and under 20 hens, I count on all my eggs being fertile.