I can distinctly remember once asking the question of what to call this moment in time, the morning of the day that will end as Christmas Eve. And my mother (requiescat in pace) looked up in thought and replied, "It's Christmas Eve Morning."
Now, liturgically, she was wrong. Vigils (Eves in the Western Tradition) are anticipatory of the greater Feast they precede. And since the Church uses the ancient Hebrew delineation of time (there was evening, and there was morning, the first day [Gen 1:5]), each new day begins at sundown, not some arbitrary hour deep in the darkness of "midnight."
Midnight is actually the mid point of the night when exactly, on September 21st at the equator?
Anyway, since the day begins at sundown, December 25th, Christmas, begins this evening when the sun sets. And any liturgical celebration after that point is Christmas. Christmas Eve Mass need not wait for midnight at all! (It is, however, quite unseemly to push the envelope any further, as some Churches are doing in this country, and call a Mass that starts at 5PM Christmas Eve Mass.)
But back to the original point. It is natural to have such a level of exuberance and unbridled excitement for the huge day which is unfolding. And so my mother's answer is certainly a faithful response, reflecting a desire that this great Feast might spread its influence and spill into the morning of the day before. Indeed, we will be in the Christmas Season for days after the 25th.
And even now, I sit and sip my coffee with a peace and growing wonder. The day will be spent in preparation of the great celebration. A feeling and sense of the season has already begun.
And so, I wish you all a Merry Christmas Eve Morning! Further greetings and celebrations await us later in the day.