We were at Disney last year from Jan 1st thru Jan 9th. There were still lots of Christmas decorations at the resorts and the parks on Jan 8th. They were still playing Christmas music at the parks also - I only remember because we were tired of hearing it by the end of the week! The Osborne Lights were still up for part of our week, but the icicles on the castle in the MK came down pretty early - maybe the 3rd or so. Bottom line, not all of the Christmas decorations will be up, but there will should still be some the 1st week of January.