we got there jan 6 once ( yrrrrs ago) and everything was down. then last trip we got there the 9th and the gingerbread house shell was still up at the GF( couldn't figure out what it was till i saw the show about it on food tv or where ever it was) and a few resorts had the chocolate displays out still.( i think beach club, vero beach and one more disney resort for sure still had their little scenes up but not other decorations)
however, disney never looks "undecorated "to me ie ws or mk is always magical after dark so not having seasonal decorations wouldn't be something i'd miss.