Peeled potatoes can be left overnight according to Martha Stewart. If put in the refrigerator and covered with water, they will stay white and be ready to use the next day.
To prep potatoes for use in a recipe the next day, take precautions to prevent them from turning brown. First, make sure the potatoes are washed before peeling to prevent the transfer of pesticides or other contaminants from the peel to the potato. Peel and cut the potatoes as desired, and put them in a bowl with a lid.
Cover the potatoes with cold water, add ice cubes, cover, and place them in the refrigerator. Citric acid powder or lemon juice can be added to the water if desired to ensure the potatoes don't turn brown. Keep the potatoes refrigerated until ready for use.