re: “Nothing about doing it in an instant.”
I’m with you. All Genesis 1:1-2 says is:
“In the beginning God created the heavens and the earth. Now the earth was formless and empty, darkness was over the surface of the deep, and the Spirit of God was hovering over the waters.”
It simply says, “In the beginning”, which tells us nothing about how long ago that occured. God may have created the universe billions of years prior to doing His creative work with the earth. The earth may have been in existence for millions, billions (who knows?) as a formless empty planet before the “week” of creation took place. It just doesn’t say.
Now, the Big Bang evidence suggests that the universe formed explosively from a given point and is still expanding away into what?? It is beyond comprehension.
And also...it never suggests that God measures his days by the rotation of our little planet Earth.