As soon as you take them out of the box, dip their bills in the water of their waterer in their brooder and make sure they swallow a drop do this one by one as you unpack them. When they are all unpacked make sure each one takes a drink on their own. This makes sure they know where the water is and have at least a sip. This is probably the single most important thing on day one. If you can't get special duckling food, you can use unmedicated chick crumbles, but they will need additional niacin. I put it in their water from capsules, many people add brewer's yeast (not baking yeast) to their food. I also put probiotics and electrolytes in their water the entire time in the brooder. (That is why I do the niacin in the water, I make 2 one gallon pitchers of "duck water cocktail" at a time and fill their waterer from them. Then the food can just come from the bag.) It seems that a lot of problems I read about with ducklings are due to deficiencies, so I don't want to take any chances there.