I added your story to the eligibility list, Lynn. I'm in the Pacific time zone, and your story was definitely posted on Dec. 31 for me. According to the FAQ on the Kerth Awards site:
What makes a story eligible?
Any story that’s finished and posted by the end of a calendar year is eligible for awards.
That says nothing about any particular time zone.
Of course, if there's an official rule I'm not aware of that is more specific, I'm sure K-Comm will let us know.