31 God saw all that he had made, and it was very good. And there was evening, and there was morning—the sixth day. 1 Thus the heavens and the earth were completed in all their vast array. Gensis 1:31-2:1 NIV
So we have the world created at last!
Putting aside the question of when this happened (already discussed), how long did the six days of creation take? Six days, you say? Maybe so. But we are talking about an ancient piece of literature about which many smart people disagree, so maybe not.
Here is a quick review of the three primary interpretations.
1. Creation took place in six 24-hour days of one earth week--the 24-hour view.
2. Each day of creation was eons in length as the earth was developed over time--the day-age view.
3. The six days are a literary device to show how things were set up (days 1 to 3 creating space and days 4 to 6 filling it) rather than a chronology--the framework view.
I can add John H Walton's functional creation view that Genesis 1 is a narrative of God assigning role and function to the earth which he had previously created.
All four have strong and weak points.
Here's a fifth proposition from the esteemed mathematician and theologian John C Lennox. In chapter 3 of the aforementioned
Seven Days that Divide the World, Lennox explains why he believes that the text of Genesis 1 to 2:2 can be read as referring to six 24-hour days that happened eons apart from each other.
So on the evening and morning of creative day 1 God says "Let there be light" and there is light! Then there are unknown eras of days as the coming into existence of light works itself out in our world. The next time we read "And God said" we get a day in which the vault of sky or atmosphere (perceived as a solid dome) is created and then the ages of time with the working out of that before the next big act which separates dry land from the waters. So the days are consecutive, but not necessarily one right after the other. Each one inaugurates a new era.