Shedding dpends on too many factors to give a tem period. It is more frequent at a younger age than an adult age. It can depend on for examples; the change in humidity, temperatures, age, diet, growth rate... etc
Shedding isnt a huge deal in my opinion. Keep the humidity up during half the day and let it dry out for a while. when you see the skin start to shed, give the chameleon a long shower followed by a drying period to help the skin progress.