Bantam crowing?

[furrybollocks]

I bought two bantam chicks in June, both of which were a week old at most. Now, a month and a half later, my guaranteed female Golden Sebright is most definitely a rooster. This morning I let them out of the coop to range, and as I was watching him he was very aggressive and dominant, and he started clucking which my three month old ladies have old just transitioned to, and then he let out a half formed crow! All of the things I've read on roosters say that they start trying to crow when they reach sexual maturity, which is another four or five months off for him! I'm bewildered. Could this be because he's around five pullets with only one other, younger roo who is much more timid?

Said guy:

 

[Tanichca]

I've had roosters begin crowing at a month old, so it's not really a sexual maturity thing sometimes. I guess that sometimes they just have so much testosterone that they can do it early.