And screen cages are best for ventilation. Glass works well also if you can keep the ventilation good. 36x18x36 would probably be good up untill about 9 months-12 months. Then a bigger cage would be good
Kammerflage Kreations keep all their adult panthers in 36 X 30 X 18 cages. They are made of screen though, not glass. they recommended that size to me when I bought my chameleon from them. I will say however, that if I had to keep my chameleon in there all the time I would feel it to be too small. I have a free range area and a large outdoor cage that is used more than the indoor cage. Just saying that size can be done and yours is even a little larger.
Minimum size isn't a bad thing. But with chameleons enclosures the bigger the better. Outdoor cages that they can get natural light when weather permits is very beneficial to them as well