I've had bantam cockerels crow in the brooder at a couple of weeks old and large fowl cockerels that were nearly a year old before they crowed. There is great variation from breed to breed and even within a breed. In my experience Mediterranean breeds and bantams have crowed earlier and slower maturing large birds have crowed much later.
My first hatch had 10 cockerels out of 17 hatch. They were pure Marans and Legbars. The Marans were very vocal, they drove me nuts! They are now in the freezer.
This batch has a rooster that is a Cochin with the mothers being Orpingtons, Plymouth Rocks, White Rocks and Cochins. The other rooster is the Son of the first rooster. Quite a mix!
I will try to get a picture of them soon.
Here it depends on peer pressure lol.
The more boys the sooner it starts.
Last batch had three boys and the attempts started around 10 weeks but squeaks I assume were tries were popping up a couple weeks in.