A nice point. Genesis 1:5 is taking note that God's division of the light from the darkness, and the naming of day and night, constituted the first day, i.e. the first diurnal cycle, in our terms.
But that leaves the "beginning" when God "Created the heaven and the earth". So what all did that include? I think the question still remains, "Whence atoms?" from a Biblical point of view.
Also, it kind of leaves the "First Day" in the lurch, creation-wise. So from your observation, there were in fact only five days of creation, plus "the beginning".
But of course, this is all just semantics and rhetoric! "It's what it is."
“So from your observation, there were in fact only five days of creation, plus “the beginning”.”
How so? Get a piece of paper, write down day one, what was referred to (land or water, etc., were not created, just moved around). Continue on thru to sixth.
I would assume the days are not literal.
There could have been billions of years between Gen. 1:1 and the creation days. Old Testament prophets briefly reference a pre-Genesis Earth, populated by nations under the guidance of the one who became Satan. He tried to overthrow God and attacked Heaven (according to the prophets). All that is where John Milton got his plot line for Paradise Lost.