No age is too young for very simple, basic training, but there's no real point trying to train a bird if you don't have rewards on hand! So your first step, before anything else, is to find something your bird loves that you can use.
Have you tried -
different kinds of seeds and nuts? (try both shelled, and unshelled - sometimes they don't care as much about the taste, but just enjoy shelling them. Big nuts like almonds can be broken or chopped up into small slivers. Millet and sunflower seeds are loved by most birds.)
different kinds of fruits? vegetables? (Our conure loves digging the peas out of snow peas, and chewing on capsicum. Sometimes texture/shape really affects whether the bird likes it or not, so try offering the same item chopped in different ways - eg. grated, chopped into big cubes, tiny cubes, matchsticks, thin/thick circles, etc. You can also try steaming vegetables, as a contrast to raw ones. You can also offer a tiny sip of fruit juice diluted with water)
eating the treats? (most birds want whatever YOU are having, so if you eat/drink some of the food first while the bird is watching, it'll usually get them a lot more interested in trying it)
Experiment a lot! You know Monty liked something if, when you hold it up, he looks excited and tries to get to it! That's when you can get started on training.
