It’s pretty unusual for us to have a Christmas Cactus (Schlumbergera) actually in bloom on Christmas day.  We have three of them – one blooms reliably around Easter and another is pretty dependable at Thanksgiving.  This one usually starts sometime after Thanksgiving, but is normally done well before Christmas.  In reading about these plants, it appears that there are several varieties that  bloom at different times of the year.  I  can’t tell them apart.