I just made a post about this, took me several weeks of waiting for him to even warm up to me and i have a long way to go, never grab him out let him walk on ur hand.
Also HANDFEED HIM, offer a variety of bugs on ur hand, try different things, that will establish u as a food provider and not a predator, took mine 6 weeks to finally snack out of mine. But i pet/hold my cham everyday, i feel that it helps reinforce that you are not a threat.