My 5" guys are filling out, getting fat and starting to get the darker colors. But i'm not exactly sure what you mean by green. My big guy, dozer, is about 9 inches, he's fattened up and his background color is a dark greenish gold, he's got red bottom fins, his top fin is beautiful and dark with beautiful spots and his black stripes on his side have lightened up. the stripe from his last bar to his tail is almost gone and the "eye" on his tail is bright and very easy to see.
I've watched him and fed him every day since we bought him at about 2 inches (last August), i never really noticed his colors changing until they were different, it seems to happen very gradually.