Christmas decorations are symbolic, festive and joyous. However, they spoil if you leave them up too long. They look out of place as the New Year loses its shiny newness. It's best not to leave decorations up too long, and it shows good etiquette. You don't have to take your ornamentation down the day after Christmas, or even by the first of the year. But don't let your tree, lights and figures linger too long into January.
The first consideration is the tree and other greenery. Check with your city, community or building to find out if there are specific days for tree collection, or specific ways to dispose of your items, such as tying up branches or entire tree. Be courteous and try to adhere to those practices. Otherwise you may be stuck with a tree carcass in your front yard until the next opportunity, which might be a while.
Another consideration to keep in mind is that Christmas is celebrated on a different day by the Orthodox, and there are other religious holidays to consider. Chanukah can end as late as the first of the year. Christians observe Ephiphany in the first week of January, and Orthodox Christmas can occur into the New Year, as late as the first or second week of January. The nativity scene and other festive decorations can remain up to observe Orthodox Christmas, as well as keep the spirit up for other holidays.
You might also want to keep an eye on the weather, and decide to take decorations down early. If you get word of a blizzard, you might consider taking decorations in earlier than planned. Decorations can freeze in place and delay your removal of the adornments, which may not be adored for as long as they remain. It can also be unsafe to take down decorations in cold and icy conditions. Be sure to choose a time that will not put you at risk, especially if you must climb on ladders or lug heavy items across large stretches of snow or ice.
The nativity scene and other figures are made to endure cold temperatures, ice and snow, but prolonged exposure causes more wear on the figures. Bringing them in before an early January blizzard can help items last that much longer. You'll get more seasons out of your holiday decorations by saving them from one more cold blast each season.