It depends on how big he is and how you feel about it.
He could certainly move now, but he'd probably be okay for another 2 to 3 months in his current set-up as well.
I moved Kitty into a 2x2x4 enclosure at 4 months old and he did well.
Make sure you establish permanent stations for dripper, feed cup and basking light, so he can learn where to find food and water and heat at all times.
I had the big enclosure set-up and running for a couple months before the move. This allowed me to get the dripper right and moniter temps/ adjust lights, etc.
basically get everything as perfect as possible before the move. This is a luxury afforded to owners of one cham and I highly recommend it.
I would say around the 6 , 7 month age so the next cage is his permanent one, but age isn't the real factor knowing that some chameleons grow faster than others try posting some pix...
My guy actually hit his 3.5 month old mark today. Pretty exciting....haha. But really tho. He weighed 20.1 grams and is 8 inches from head to tail.(SVL?) Just two weeks ago he weighed 10.9 grams. that nearly 50% in two weeks! I would like to see some pics of yours. Mines a veiled and I will get pics up ASAP for the comparison.