When will my boy Roo become a man Roo?

[scoopy82]

Thanks guys - I was gonna say "when will my rooster start having sex with my hens" but that just seemed a little too clinical

I have 2 roosters in with my girls - both muts, the more mature who has been crowing for a little while is Isa cross Spangled Hamburg, and the other is probably Spangled Hamburg cross SLW, he hasn't said boo yet but going by his attitude (not nastly, just very boy like) and his lovely tail feathers I'm guessing he has to be a boy, might post a photo later just to see what others think.
Anyway those two are in with 2 girls that hatched at the same time and 4 hens that have been laying for a season (2 leg horns and 2 isa's). I haven't witnessed any funny bussiness yet and haven't bothered to check the eggs, but I suppose it will happen when everyone is ready. Just thought I'd ask if there is a general age that these things happen, like chicken puberty