Although it is not certain the exact date or time of the first Christmas Day, we at least know how it happened:
– And there were in the same country shepherds abiding in the field, keeping watch over their flock by night.
– And, lo, the angel of the Lord came upon them, and the glory of the Lord shone round about them: and they were sore afraid.
– And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people.
– For unto you is born this day in the city of David a Saviour, which is Christ the Lord.
–> from the Gospel of Luke chapter 2 verses 8 through 11