The Bible says "one day is as a thousand years with God" (2 Peter, 3:8). If taken as a metaphor, rather than literally, we cannot really even compare our concepts of "time" with God's, because perhaps it really IS beyond our comprehension.
Our "time" is based solely on our relationship with our Sun. Each "day" is one revolution of Earth on its axis; each "year" is one Earth-orbit around our Sun.
Surely, God's realm is in no way similar to our own realm, including the concept of time.
- If one "day" to God is as a thousand of our years, that would mean He created our world in a period of six to seven thousand of our years.
- And, if one "day" to God is more like a MILLION of our years, it took six to seven million of our years to create our world.
- And, of course, if one "day" to God is more like a BILLION of our years, well...there we have it...our world would have been created in six to seven billion of our years.
- But, as far as we know, our planet is only about 4.5 billion years old (our 'years') - meaning that Earth has orbited our Sun 4.5 billion times so far.
- Perhaps, then, one day to God is more like 750 million of our years, based on six of God's "days" to create our world.
And, there may be many more 'universes' than we think. I often think of our solar system and our universe as part of a 'grand structure'; a 'living structure'...where life abounds everywhere there are Suns (stars) and planets and moons and all the other things we've come to understand about our own small sector of everything. It just makes sense to me that way.