Evening came, and morning followed–the fifth day. (Gen 1:20-2:4a)
https://bible.usccb.org/bible/readings/021125.cfm
Today we come to the conclusion of the First Story of Creation in the Book of Genesis. The formula that concludes each section, “Evening came, and morning followed,” may seem strange to us, but that the day begins at sundown makes perfect sense to a culture that follows a lunar calendar. It also explains why the Liturgy begins Sunday and special feast days with First Vespers at sundown the day before. It’s fairly obvious that this First Story of Creation is the work of a priestly imagination. God neatly wraps up the work of creation in 6 days and then rests on the 7th day (the sabbath)—just like we’re supposed to do!