Hi,
The earliest I've have quail crow is 35 days old, but this is to young for breeding.
I select 5 week old males for breeding, and place them with 6 week old females as they take a little longer to mature than males.
Very often, the females start to lay before 7 weeks old and the young males are quite capable to fertilise any eggs.
Just to be on the safe side, I don't collect eggs for the first 10 days after 1st egg is layed.
You should by this time get loads of fertised eggs for your incubator.
Ironsun.