The great thing about mashed potatoes is that they can be prepared in advance, freeing up time on busy days. In general, mashed potatoes can be made up to two days ahead of time and stored in the fridge. When you're ready to eat, simply reheat the potatoes on the stove or in the microwave. For best results, add a little splash of milk or cream before reheating, as this will help to restore their creamy texture. With a little planning, you can enjoy homemade mashed potatoes any day of the week.