That very well could be the reason as I have always kept a few males. Maybe the males get the females hormones going sooner? I have a cage that is 8'x 3' and can be divided in two. i incubate about 35 eggs at a time for approx 30 chicks. At 3 weeks (or less in the summer) they are out of the...
That's pretty late, is it cold where you are? In the South they lay pretty well through the winter although not as consistent as when the days are longer and warmer. My experience is they start to lay about 9 weeks.
They do love the dust box! Males are not very loud although they do have a crow. If you search Coturnix rooster crowing on google or I think there maybe a link on this website to a video that will give you an idea how they sound.
Unless you have a very big cage and probably even if you do, the roos will start aggressively fighting at about 6 weeks. I separate at that time 6 to 7 hens for one roo in separated pens. Good luck they are interesting birds and very tasty out of the crock pot on top some wild rice!!
I've been raising coturnix for a couple years...enjoy the hobby! Hens lay at about 9 weeks the males will start to show aggression and well...there maleness as early as 6 weeks.