veileds generally begin showing their adult coloration and patterns between 6 to 8 months according to what i have read.
Idoneous is still pretty much a baby, so you are going to have to wait awhile to see his true colors come out!!
It depends on the chameleon's genetics and size. Some of the huge babies that look twice their age have colors by 4 months, but most tend to get them between 5-8 months.
I have been taking as many pictures as I can, but he is still very shy and I have been trying to ease him into trusting me. I can hold him without stress colors, but only for a minute or two.