Was it 7 days, 24 hour days? [Related topic: https://ebible.com/questions/3901-did-the-author-of-genesis-ever-intend-the-7-day-creation-story-to-be-taken-literally]
Genesis 1:1 - 31
ESV - 1 In the beginning, God created the heavens and the earth. 2 The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Creation: 1st Day
Gen 1:3 - KJV
The "Light" that the Bible is referring to in above verses is Jesus, not the light coming from a celestial body. This is for the reason that God only created the Sun, Moon, and the Stars on the fourth day.
Creation: 4th Day
And since, celestial bodies were only created in this specific period, we can assume that the timing applied in the first day of creation is not the Earthly time (24hrs)
When God created Jesus in Gen 1:3, time element is present.
Also see Jn 1:1. "In the beginning was the word. And the word is with God. And the word is God".
Jesus (God's Word) denotes time.
Verses Rev 1:8 and Rev 22:13
Our Jesus is the Alpha and Omega. It clearly implies that Jesus controls time.
Moreover, it is clearly God's time that God ruled during the period of His creations.
Let's jump to Gen 2:4.
As the verse said, "these are the GENERATIONS".
If we do a little research, the average span of a single generation is 25 years. And the bible says generations. It could mean thousands, millions, and billions of generations before creation of Man took place.
Disclaimer: I could be wrong with this but may God's Holy Spirit shine upon us in Jesus name. Amen :)