1. There is a reason for the sun and moon being created on the 4th day rather than when the earth was lighted. Imo, that reason was that for the water to be evaporated from the earth to create the suitable atmosphere for the designer, Jehovah's plans for the planet, intensive heat was applied via the Holy Spirit of Jehovah, that member of the trinity which Jehovah sends out throughout his universe to perform the work which Jehovah wanted to do. The Holy Spirit applied that intense light/heat.
2. It was not until day four that the day became 24 hours, since that was one of the things these bodies were to determine upon planet earth according to the text.
3. The length of days one, two, three and four are unknown since the length of them is not given in the text. I include day four since we do not know how long it took for the sun, moon and stars (likely the stars of the Milky Way Galaxy or the ones closest to the earth) to be created.
5. Days five and six were 24 hours since the sun and moon were completed.
BUZSAW B 4 U 2 C Y BUZ SAW.
The immeasurable present eternally extends the infinite past and infinitely consumes the eternal future.