that is a little unusual. usually at that age they just about explode out of their skin. Well atleast that was the case with my cham. At 4 or 5 months it took a matter of a day or hours. I do know as they mature they shed less and less and when they become adults they usually don't do whole body sheds, but shed in parts. Have you tried misting him directly with warm water, or taking him in the shower? Is your humidity ok?
This pic was just taken about an hour ago. He seems fine other than the shedding. This is my first Chameleon I use to have Igunana's and they would shed in a day or 2 so I wasn't sure if this was normal or not for a chameleon.