That's about when mine start too. Although I had been leaving a lowly lit light in the coop for a little bit of extra warmth and my main roo started crowing ALL night..
Thankfully he is a Silkie, so he's not as loud as some breeds.
They usually start around 5:00 a.m. With all the Christmas lights on the street behind us, they have been crowing pretty much all night. Hopefully they will calm down now, though.
my New Hampsire roo doesn't crow when I'm in the house...
oh, wait... maybe I just can't hear him because the house is pretty sound proof...
I think he starts around the very first light of dawn.
I had one that crowed day, night, whenever... and if it was more than half full moon? ALL the time.
that was my little silver sebright rooster, who was beautiful but thought he was going to Kick My Butt EVERY time I went out to the chicken run. never mind he weighed like six and a half ounces...
tough little booger...
but man, the all-night-full-moon crowing. nope, he didn't get to stay.