At two to three months, he'll need 80% feeders (crickets, phoenix worms, small butterworms) and 20% greens. He probably won't want many greens at this age. However, I would put greens in his viv with him and use collards, mustard, turnip greens. You can use some romain lettuce, just not much because that will give them more water than nurishment. About the pre packaged salad mix, it depends on what's in it. The only thing that head lettuce is good for is a beardie that is dehydrated. Head lettuce has no nutritional value at all, the romain and green, read lettuce are better, just not that much.