I currently am not hatching quail, but when I was, they were the Japanese Coturnix Quail, and took about 18 days to incubate.
I'm waiting for the feed situation to improve here in Panama, before I raise quail again. The feed stores sell chicken feed (even that was unavailable for about 6 weeks and my chickens were suffering with corn, cooked rice, and foraging on my half-acre while I fed their food out to my quail. Game bird feed or quail feed has not been available for the past many months and when asked when they anticipate having it again, I'm told "After Covid". I attempted to correct the balance of amino acids and protein of the chicken feed to accommodate my quail, but was unsuccessful. It was evident that my attempts were failing by their lack of weight gain, poor eggshell quality, exceptionally low egg count or internal laying that would ultimately lead to death. For the birds that weren't sick, I sent them to freezer camp. For those that were showing signs of illness, I humanely put them out of their misery.