i do mine at 12 weeks, they havent started moulting at that age so theres no pin feathers, also the testosterone hasnt kicked in so it tastes nicer i think. kind of like how veal tastes different to normal beef.
if you wait till 16 weeks you gain an extra 500grams in weight, but you have to deal with pin feathers and the feed to get the extra weight on. some people do it at 20 weeks. in the end its just up to personal taste. the chinese buy up big time at the auctions for the chinese new year and they dont seem to care about age.
i chop off the back legs and mince them, then cut the carcass in half so you still have the breast on the bone, roast it for around 30 mins, let it rest for 5 mins, then slice the breast off the bone, slice the breast up and season with salt and pepper. my dogs get the offal and neck, one of them eats the head, beak and all. what amazes me with him is that they free range with him and he doesnt touch them! i'm lucky he's a smart dog. sometimes i'll make a stock with the bones if i can be bothered after all the buthering
i forgot to mention i only bother plcking the drakes, the girls i just skin and cut off the good bits, my hands are too big to get inside the carcass to gut the young ducks! i crumb the young duck breasts and make snitzels or parma's out of em, tasty.
my dog "bullock" duck bodyguard, he's a blue heeler or australian cattle dog if your wondering.