about every month or so until around 6-7 months, then it slows down
quoted from the chameleons dish-Throughout their lives, chameleons will shed many times. When they are younger, they shed more often, gradually shedding less as they mature. Chameleons that about to shed will gradually lighten in color, and a day or two before shedding, the first layer of their skin will look foggy, even a bit wrinkled (see first picture to the right). This layer of skin will turn white and will naturally come off.
There is no set pattern or time schedule for shedding (don't worry if your chameleon doesn't shed exactly once every ___), but there are ways to gauge if all is going well. Chameleons that are in the peak of health and kept in a proper environment should be able to shed with ease, usually in one day. If the environment and health of the animal are not ideal, slow (often dry and retained) shedding may occur. If an animal is having trouble shedding, consider the reasons for complications such as environment and care.
My 4 month old panther has shed 3 times in 2 months but around 1 a month would be about average. All depends on growth rate, some will grow quicker than others depending on conditions, the quicker the growth the more it will shed.