Hi Qusilover and welcome to the Forum.
Try putting a few mealworms in the cage. A female will eat them immediately but a male will pick one up and offer it to a female. But this may not work if they are not yet fully mature.
At this time of year, when the days are getting shorter, its normal for quails to slow down or stop laying, and for youngsters not to become sexually mature until the Spring, so it may be hard to tell whether you have a female who isn't laying yet, or an immature male who is not yet in breeding condition. If you do have one of each, it would be best to get at least one more female as once puberty does hit the boy's hormones he may be too much for only one girl, who may get pecked or worn by too much attention. You're right to want to get a group settled together ASAP, as it becomes increasingly difficult to introduce a new bird to an established group as time goes on and they settle together. Quails often do take a long time to settle as a group, so if you can decide between just having females, or having a mixed group and giving the male more than one girlfriend, now is the time to do it. But as I said, this may not be straightforward at this time of year, as you are finding! Males will frequently live peacefully together over the winter, but may begin to fight once the days begin to lengthen and they come into breeding condition. Sorry if this isn't much help, its hard to advise without seeing the birds, and even then it's not easy to tell. But once you do get an active male, there will be no doubt in your mind! Do let us know how you get on.
