Room temperature, day of: cover loosely with a towel. Eat within 24 hours.
Fridge, up to four days: airtight container. Reheat in a 300°F oven for six minutes, or 15 seconds in the microwave.
Freezer, up to three months: wrap individually in plastic, then in a zip-top bag. Thaw at room temperature, then warm in the oven.
Fresh icing is a gift. Keep icing separate if you can, and apply after warming — it re-melts into the folds.