Thank you for the photo. I don't see evidence of a molt, only a nicely feathered budgie. There may be a series of juvenile molts and then these birds will molt 1-2 times annually. These molts, often referred to as the prenuptial and postnuptial molts. occur in spring and autumn respectively. The pattern of molting is orderly and in the following progression (with some overlap): the inner primaries; the outer primaries; the secondaries and tail feathers, and finally the body contour feathers. It is usually bilaterally symmetrical and is paced so as to avoid loss of flight capacity at any time.
Proper molting and replacement of feathers is heavily dependent upon diet.
Seeds should comprise less than 20% of his (I believe) diet. A diet of mainly seed and nuts has excessive fat, carbohydrates, and phosphorus; marginal protein; adequate vitamin E, and are deficient in amino acids, calcium, available phosphorus, sodium, manganese, zinc, iron, vitamins A, D3 (necessary for efficient absorption of calcium), K, and B12, riboflavin, pantothenic acid, choline, and available niacin. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard-boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese - yes, these low lactose foods are safe, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat. Here are some tricks in transitioning him to pellets: https://www.harrisonsbirdfoods.com/using-our-foods/diet-conversion/
Please respond with further questions or concerns if you wish.