From what date to what date, can the Spode Christmas dishes be used
and maintain proper etiquette?

HI,
The traditional Christmas period is from Christmas Eve to Dec. 6,
Epiphany, the date when the three wise men are considered to have
visited Jesus.
I am conservative, living in Germany, where most people put up their
Xmas trees on Dec. 23 or 24 and dispose of them after Jan 6.  I
suppose if people in your area put up their trees earlier and/or
dispose of them later, it would be acceptable to use Christmas china
during that period.
Myoarin

I believe my friend Myoarin means January 6.

Thanks, Tryx, he sure does!  (Those darned fingers just type whatever
they want, and I am a bad proofreader.)
Myo