For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
To use 2 Peter 3:6-9, "to The Lord, a day is as a thousand years"--the attempt to use that verse to make the earth multiple millions or billions of years old, is to turn Biblical time language into utter nonsense and incomprehensibility. 2 Peter 3 's context is to show that God's patience is as infinite at 1,000 years as His patience is for one day. It has nothing whatsoever to do with how we interpret the Bible's time period terminology.
The bible doesn't tell us. But this I know, when God spoke it became.