Males tend to develop them earlier, but nobody can say for sure when it will happen. The formula is going to be based primarily on genetics of your fish, diet, water conditions, and stress. Keep a happy, well fed, fish in clean water that has good genetics and your fish will be at its best.
There are lots of opinions on what 'the best' food, water conditions, etc will be as well. Do your research. There are also many that have turned around a 'bad' fish they recently acquired and a few stories where one person was taking care of a fish just fine but it grew a nice kok after another person buys it - and between the two people there really was no change in how the fish was cared for, it may have just been aging. Post some pics too, or at least take some for yourself, it's much easier to see progress if you take a photo of the guy at least once a month.