I started offering my veiled greens at about 2 months.
started with mustard greens. Freshly picked. with in 30 seconds he was devouring them!
I would put them in the same location in a shallow small bowl so they stuck out near his basking spot.
I also use different types of lettuce, just started butternut squash (here's hoping). I also have hears GREAT things about baby tears cham's regardless of what type seem to love them.