That is factually incorrect.
The Big Bang, according to the theory, was a point in space and an instant in time at which spacetime and matter/energy originated. The theory says nothing at all about what existed before then. In fact, the question is meaningless under the terms of the theory.
It also says nothing at all about why the BB occurred. Which means we are perfectly free to assume, in full compliance with the BBT, that it happened because God caused it to happen.
This is in full compliance with standard Christian theology by which God stands outside space and time, in Eternity.
As for Creation and its Days, here's the way I see it. YM obviously varies.
Breaking the first few verses into paragraphs may help.
In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness [was] upon the face of the deep. And the Spirit of God moved upon the face of the waters.
And God said, Let there be light: and there was light. And God saw the light, that [it was] good: and God divided the light from the darkness. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
It then goes on, of course, through the remaining Days.
As I see it, this means God created the universe in the Beginning and let it run, possibly according to the Big Bang Theory. The earth eventually developed, but it was shrouded in darkness. God then turned his mind to making the formless and void earth a fit place for his Children.
He Spoke for the first recorded time. He caused Light to be on the Earth, then divided it into night and day.
He then goes on thru the remaining days, each Day starting with Him Speaking something into existence.
This organization of the discussion does not appear until verse 3, so to my mind this means verses 1 and 2 occurred before Day One.
We can also get into a long discussion about whether each Day refers to a literal 24 hour period, but I'll let that one just lay there.
You are, of course, entirely welcome to believe otherwise. I just find it a little annoying when someone announces that their personal interpretation of a passage not written as a scientific treatise is the only possible one. Especially when the concepts needed to write such a scientific treatise were well beyond those of the (human) author.
Again you err
the big bang covered all evolution
in fact, that is why the big bang helped promote all evolution, it provided a means to explain long time periods to explain what clearly does not happen before our eyes
in other words, it used an excuse of not being able to see it to prove it happened
It is a fable, not science, and only the foolish believe in evolution and the big bang