The Word of God states in Genesis 1:1> in the beginning God created heaven and earth; and the earth was void and without form.
The above statement are book-ends referring to the creation and after the passing away of this the first earth.
This is exactly what Revelation 21:1 also reveals.
Even affirmed in Isaiah 46:10 > I have declared the end from the beginning.
You can’t have a any beginning earlier than Genesis 1:1 in the Word of God. HE is perfect in all His ways.
Everything in the Bible is about history of the first earth from God’s omniscience and point of view because what He has purposed will always come to pass. There is no circumventing His sovereign will.
The gap theory of pseudotheologians is nothing but a deception aimed at causing doubts in the minds of believers about the veracity of the 6 day creation account of Genesis.
As regards “light” it states in Genesis 1:3 that God brought light into existence with His words.
The sun and moon placed in the firmament on the 4th day only reflect the light created in the beginning towards it’s intended destination and purposes.
We have to differentiate between the source of light and the celestial bodies that merely reflect that light.