I've never seen a rooster wait that long to crow, but I guess anything is possible.
You did not say if you have a rooster or not. The mating ritual is also a dominance ritual. I've seen the dominant hen in a flock that did not have a mature dominant rooster in it go through the mating ritual with other hens. She was maintaining her dominance over those hens. A rooster will try to mate a lot more often than the hen. There is an urge to reproduce with him that is not there with her, but mating behavior does not necessarily mean you have a rooster.
Since it is sometimes a dominance thing, mating behavior does not guarantee that the pullets are ready to lay. It is a real good sign, especialy if it is a rooster, but I have seen a 13 week old pullet not resist mating with a young cockerel her age. She did not start to lay for another 7 weeks.
When they start laying is an individual thing. Breed and time of year enters in it too. I normally get the first egg somewhere around 19 to 20 weeks of age, maybe half of them are laying by age 23 weeks, and practically all of them are laying by 28 weeks. Looking at the breeds in your signature and how many chickens you have, I'd expect yours to maybe follow somewhat close to this pattern. I'm not sure about the Silkies and the Brahma.
I have had some start to lay by 16 weeks. Not many, but some. And I've had some go well beyond 28 weeks. As I said, it is an individual ting.