Shipping during the holidays is a stressful time of year. The carriers are especially hit hard with trying to get all the influx of presents trying to get to their destinations, on top of the normal shipments for business's and deliveries.
In order to get you package to its destination on time, and this especially includes Christmas time present, the carriers have special Ship By dates to ensure your package makes it on time. Please see the links below for the various carriers that have these times posted:
If shipping from within/to the States: