Well alot of people on here do not agree with feeding pinkies unless it is a female that has just laid eggs. im kind of on the fence as to wether or not they are okay, because a friend of mine keeps his male on a diet consisting of greens and a pinky once a week or so and he is huge, nearly 900 grams and extremely active and healthy, so you see it can be a good diet for some beardos. if you are going to try using pinkies i would say that the size of your beardie plays a much larger role than the age. you will want your beardie to be over 16 inches so that the natural kink in a young bearded dragons intestines has opened up. besides that just dont over do it with the pinkies, too much fat will make you beardie very lethargic and it may even stop eating,this is what happened to mine (because of crickets gutloaded with catfood not pinkies but still the same thing). so just know your beardie and if it starts acting differently you should probably cut the pinkies out