I start thinking about Genesis 1 by quoting from Genesis 29:18-28:
And Jacob being in love with her, said: I will serve you seven years for Rachel, your younger daughter. Laban answered: It is better that I give her to you than to another man; stay with me. So Jacob served seven years for Rachel: and they seemed but a few days, because of the greatness of his love. And he said to Laban: Give me my wife; for now the time is fulfilled, that I may go in unto her. And he, having invited a great number of his friends to the feast, made the marriage. And at night he brought in Lia, his daughter, to him, giving his daughter a handmaid, named Zelpha. Now when Jacob had gone in to her according to custom, when morning had come he saw it was Lia. And he said to his father in law: What is it that you meant to do? Did not I serve you for Rachel? Why have you deceived me? Laban answered: It is not the custom in this place, to give the younger in marriage first. Make up the week of days of this match: and I will give you her also, for the service that you shall render me other seven years. He yielded to his pleasure: and after the week was past, he married Rachel.
The Aramaic peoples used timespans in figures of speech. In this passage a week is made to stand for a year.
This being so, we have at least one example in Genesis where figurative language is used with respect to timespans, and consequently there is no a priori reason to assume that other timespans in this book must be literal. This being the case, questions about whether specific timespans should be taken literally or figuratively will need to be judged on their own merits, taking into consideration the context and the literary type.
So with respect to Genesis 1, it is not unreasonable to ask whether it must be the case that its purpose is to present a literal chronology of God’s work of creation. Having said that, though, there are at least two dogmas that surely may be affirmed from Genesis 1 without recourse to the thesis that it presents a literal chronology: first, the fact that God created everything, and that He did so ex nihilo; secondly, that He created Man in His image.
As one who previously insisted that upon a young earth I am sympathetic to the interests and concerns of those who do so, but I no longer think that the Christian Faith stands or falls upon the answer to this question. To my knowledge the Church has never defined a dogma concerning the chronology of Genesis 1, and that fact alone makes me reticent to be dogmatic about it myself.