Mine Ate Fruits At 3 Months And I Built One Day Entirely Of Fruits Into My Feeding Routine At 6 Months. From 3-6 Months The Protein Has To Be Offered With Fruits Since They Are Growing So Fast. Also When They Get To 6 Months Of Age One Day A Week Without Food Is Good For Them Also. Lets Their Digestion And Excretion Catch Up With Their Appetite.
i dpnt think its an age requirement as much as a size requirment! and maybe if your chameleon was arround 8-9 in. total lenght and it had a wide enough mouth.
Stay away from spinich, tomato and brocolli for sure, even for gutloading.
There are multiple reports of these vegetables creating problems for reptiles.
People will debate this, but, I feed my veiled only dark green leafy greans such as, Collard greens, Kale, butter lettuce, etc. ... no spinich or fruit
He eats them like crazy and with these greens I am providing him with an additional source of calcium and moisture.
Concerning the age to start: I say offer them now and continue to offer them. If he isn't interested today, he will surprise you tomorrow or next week by ripping them up and devouring a really surprising portion.
The problem with trying to control when or how often is that you will at some point or another not be providing them on a day he wants them. I have experience with a veiled eating artificial plants in the enclosure. Something I am sure he would not have done if he had the real greens available. It's not expensive or difficult to add these to his routine. I would start now and wait for the fun to begin. It's amazing watching them tear the greens apart.
I have given mine greens (dandelion, kale, collards, endive, small amounts of ROMAINE lettuce, etc.) and veggies (diced sweet red pepper, diced carrot, diced sweet potato, diced squash, zucchini, etc.) and a little fruit (apple, pear, melon, berries, etc.). They also eat the pothos in their cages sometimes...especially the females.