Post #30 disagrees.
It all depends on the definition/delineation of when a day begins.
In the Jewish understanding of the first century—and even to this day—the new day begins at sundown.
By the way this is the understanding of “day” in the Orthodox Church and in traditional Catholocism. A Feast—such as Christmas—begins at sundown. Hence “Christmas Eve” services.
Sunday begins with Vespers on Saturday evening.