the "day" is founded on verse 5 and it says nothing about being the 12 hours of daylight and 12 hours of night. Thats you speculating. The 24 hour period we call a day depends on the earth's rotation on its axis while it rotates around the sun. The sun was not created until the fourth day (Gen 1:14). There is no textual reference in the bible that suggests that the first three days were the same as todays 24 hour periods.
ASV 1 In the beginning God created the heavens and the earth.
2 And the earth was waste and void; and darkness was upon the face of the deep: and the Spirit of God moved upon the face of the waters
3 And God said, Let there be light: and there was light.
4 And God saw the light, that it was good: and God divided the light from the darkness.
5 And God called the light Day, and the darkness he called Night. And there was evening and there was morning, one day.
The point is that whoever compiled Gen 1:1-5 did not know that the earth rotated, per the above:
"And God called the light Day, and the darkness he called Night."
There is no better love between 2 people than mutual respect for each other WT Young, 2002
Who gave anyone the authority to call me an authority on anything. WT Young, 1969