At what age to cocks start crowing?

[pinkmagic1]

I'm sure its been asked before, but at approximately what age do cocks start to crow?

Mine have varied a lot. Our main cock was about 6 months old, but I had a 10 week chick start crowing earlier this year (hilarious). The others have all been about 14 weeks old, now they are 18 weeks and very nearly as loud as 'Daddy'.

I do wonder if our original cock crowed late because he was only with hens. All the chicks we've had this year have had the benefit of listening to him yell his head off 100 times a day!