As the great Thorin Oakenshield, King Under the Mountain himself, said, "We still call it Durin's Day when the last moon of Autumn and the sun are in the sky together. But this will not help us, I fear, for it passes our skill in these days to guess when such a time will come again."
As it passed my skill in predicting Durin's Day to be the 10th December!
Further research into the matter proves that Durin's Day is actually the first day of the last crescent moon of Autumn; not the first day of the last new moon as I had earlier supposed.
That puts Durin's Day as early as 11th December or as late as 13th December! I'm going to play the middle and call 12th December my own observation of Durin's Day. Again, moon rise should be in the morning, moon set in the late afternoon or early evening.
Anyway, happy Durin's Day, whenever it comes your way!