I quoted a couple of scriptures earlier of the length of days in the Bible. Psalms 90:4 says "For a thousand years in your eyes but as yesterday when it is past, And as a watch during the night." Basically a thousand years to God is like a 24 hour day to us.
2 Peter 3:8 says "However, let this one fact not be escaping your notice, beloved ones, that one day is with Jehovah as a thousand years and a thousand years as one day."
This is pretty clear that when a day is mentioned regarding God it a different amount of time to us as humans.
The Hebrew word used here for "day" ("yohm") also has a variety of meanings, including "a long time; the time covering an extraordinary event.", so it could have been any length of time.