If you are gutloading well, you can dusting 3 feedings with plain calcium and the d3 and multivitamin twice a month each. If you follow the normal forums dusting schedules etc. But if your gutload is lacking (which it shouldn't be as they should be getting most of their nutrition from the gutload) dust every feeding with plain calcium except for when dusting with the others.
Your set up needs More branches and plants. I strongly recommend not only relying on exo-terra and other bendable vines as your only branch, use actual branches and dowels too. You need enough plants to be able to easily lose you chameleon.
At the top of the page, next to the heading that says Species, there is a ... If you click on that it brings you to the Resource section. There you will find some awesome suggestions on lighting, feeding, caging, species specific care advise and other topics. Definitely worth the read.