Part of what I do in my classes is have the students read through the Genesis account, making a list of what happens on each day. The reason I do this is that we often determined what meaning to go with for a particular word based upon its local, and then global context (with non-local or Scriptures from over the Bible). Side note: I personally extended my own study to other creation accounts from the ancient near east to see how they thought of creation.
So we begin on Day 1 and work our way through Day 6 asking if there is any indication of how long various events took. Most of the events it is hard to say, like we can’t say ‘oh I know just how long it would take God to separate expanse from expanse.’ One interesting day though is day 3 where God commands the Earth to produce vegetation–verse 12 is very particular which reads something like:
The earth produced vegetation: seed-bearing plants according to their kinds and trees bearing fruit with seed in it according to their kinds.
This is the first thing that provides some context to how to understand what a ‘day’ is supposed to mean. You can ask, why does the text tell us that the Earth produced vegetation, especially noting that they were seed-bearing plants. How long does that process usually take? It is an interesting question I think, and it would be reading something into the text to somehow force it to say that this process was supernaturally quick on ‘day’ 3. This type of language is strongly similar to Psalm 90, which is attributed to Moses:
3 You return mankind to the dust,
saying, “Return, descendants of Adam.”
4 For in your sight a thousand years
are like yesterday that passes by,
like a few hours of the night.
5 You end their lives; they sleep.
They are like grass that grows in the morning—
6 in the morning it sprouts and grows;
by evening it withers and dries up.
There is a lot there to unpack but I will leave it to you and others to decide. There isn’t much else in terms of a time marker other than all the stuff that is packed into day 6-
God creates land animals (could be quick), God makes man (could be quick), God puts man in the garden, God plants a garden (where the trees and such grow out of the ground), God again makes the birds and land animals (a second time?) and the man names all of them (how long would that take?), did the man do any work on this day in the Garden as well? (there’s only 24 hours to work with here ) , the man needs to realize that he’s lonely (did the man enter into a state of loneliness after just a few hours?), the Lord knocks the man out with anesthesia and does a surgery making the woman (this probably took at least a few seconds), the man has a deep emotional response and bursts forth in poetic glory (it takes me a lot of agony before I burst forth in poetic beauty at the lifting of my agony but maybe that’s just me), God also gives them the creation mandate listed in chapter 1 and they go to bed, only to find out God is sleeping the next day when they wake up.
The point of all of this is that the text itself describes ideas and concepts locally that have a measure of time built in to them, some of which seem to be quite a bit longer than 24 hours. This does not take one to billions of years, but it does free up reading strict 24 hour periods into the text.