Exodus 18:13
King James Version
13 And it came to pass
on the morrow, that Moses sat to judge the people: and the people stood by Moses
from the morning unto the evening.
Looks like "the morrow" starts in the "morning".
This is just in Exodus. Examples like this are strewn throughout the scripture.
All days begin in the morning. Sabbath, too.
Revelation 3:9
“Behold, I will make them of the synagogue of Satan, which say they are Jews, and are not, but do lie; behold, I will make them to come and worship before thy feet, and to know that I have loved thee.”