Generally, people have until January 6 before they have to take down their Christmas decorations. That's almost a good two weeks. That should give everyone plenty of time to put away their ornaments, throw away their fruitcakes, and dispose of their trees.
But I think it's an unwritten rule that people have about 5 hours to put away their Halloween decorations. Because while seeing pretty lights and signs that read "Peace on Earth" are appealing for most of the winter, nobody wants to read "OOGA BOOGA!!" on anyone's lawn in November.