Light = Day or Daylight = Morning and Evening, Gen 1:5;
Darkness = Night, separated from the day, Gen 1:4;
Morning and Evening = Bookends of the Day, Gen 1:5;
Therefore: Day begins at Morning, and ends at Evening. Make sense!
This is a very brief study of when a day begins, in Scriptures. Specially pointing out the finer points missing in most teachings we find, about this subject.
And Elohim said, “Let light come to be,” and light came to be.
(Gen 1:3 TS98)And Elohim saw the light, that it was good. And Elohim separated the light from the darkness.
(Gen 1:4 TS98)And Elohim called the light ‘day’ and the darkness He called ‘night.’ And there came to be evening and there came to be morning, the first day.
(Gen 1:5 TS98)