Biblically, each day of Genesis 1 at most could be 1,000 years each (Ps.90:4; 2 Pet.3:8).
So the 6 days of Gen.1, and then the 7th day of Gen.2 when God rested, could at most equal 7,000 years. That's by allowing the Ps.2:4 and 2 Pet.3:8 Scripture to interpret one of God's days as being like a 1,000 years.
It's also Biblically determined with what God declared to Adam, that "in the day" he ate from the wrong tree he would die (Gen.2:17). Adam lived 930 years. Methusaleh lived the longest at 969 years, but still short of a 1,000 years. Thus God's prophecy that "in the day" Adam disobeyed Him that Adam would die, Adam did literally die within that 1,000 year day reckoning.
It's been roughly 6,000 years since God formed the man Adam in His Garden (per Bishop Ussher's Bible chronology of begats in his 17th century work The History Of The World, from Christ back to Adam put at 4004 B.C.).
6,000 years - to creation of mankind
1,000 years - 7th day God rested
6,000 years - from 4004 B.C. of the man Adam to today
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13,000 years
+
1,000 years - Christ's future "thousand years" reign on earth.
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14,000 years total
Per the New Testament, the "day of Christ" (2 Thess.2:1), or "day of The LORD" per the OT prophets, that day is put for the Rev.20 "thousand years" of Christ and His elect's future literal reign over all the nations with a rod of iron. That day is referred to as a day of 'rest' per Hebrews 4, modeled after God's 7th day of rest. Thus two cycles of 7,000 years, Christ's day of rest still to come with His return to this earth to start the Rev.20 "thousand years".
That would put creation of mankind (aadam) at no more than 7,000 years ago, and definitely no more than 13,000 years ago.
That still does not explain how old the sun is, nor how old this earth is.
When Genesis 1:1-10 is properly read (even by the KJV Old English), God's creation of the earth is declared in Gen.1:1; there is no statement of literal earth creation after that verse. The later appearance of "dry land" underneath the "waters" is not a creation statement. It's a statement about uncovering of the earth that was already underneath the waters first mentioned back at Gen.1:2.
In Rev.12:3-4, we are given a hint about Satan's rebellion of old. Within that same timeframe of Satan's rebellion we're shown a beast kingdom that he rebelled against God with. It had ten horns, seven heads, but only seven crowns. In the next chapter of Rev.13:1-2, we're given another beast kingdom example, one that's to have ten crowns, and it's linked to the type of kingdoms Daniel was given to see, which were literal kingdoms upon this earth.
In Ezekiel 31, God gives a Message to Pharoah king of Egypt, and then immediately begins describing "the Assyrian" as a cedar of high stature, his boughs multiplied above all the trees of the field. And under his shadow dwelt all great nations (Ezek.31:6). Then in Ezek.31:8-9, God describes him being in His Garden, that no tree in the Garden of God was like him in his beauty. God then says He made him fair by the multitude of his branches so all the trees of Eden in the Garden of God envied him. Problem: the flesh king of Assyria never was in God's Garden of Eden, so who is God really talking about with that analogy? It's Satan as that high cedar originally in God's Garden, before he rebelled.
In that Ezek.31 high cedar analogy about Satan, the fowls of heaven and beasts of the field that dwelt under his branches are referred to as "great nations". That's about the kingdom of ten horns, seven heads, and seven crowns that Satan originally rebelled against God with, drawing a third of the stars (angels) to earth with his tail (per Rev.12:3-4).
By the time of Adam and Eve in God's Garden, Satan was already in his role as the temptor. He had already rebelled against God, and was in his role as the adversary, symbolized by "that old serpent". So when was that time before he rebelled, the time when God had set him up as that high cedar in His Garden of Ezekiel 31, and when all great nations dwelt under his boughs? It was long before the time of Adam and Eve. And it hints that God's creation of the earth was before the start of this present world beginning at Gen.1:2. The earth being totally engulfed under the waters of Gen.1:2 reveals God ended a previous time upon this earth, the time of Rev.12:3-4 when Satan first rebelled with a beast kingdom of seven crowns, and committed the first sin.
Science estimates the last ice age was around 11,000 to 18,000 years ago. I think it was closer to 13,000 years ago, starting at Gen.1:2 with God shaking this old earth to end Satan's first rebellion, and then covering the whole earth with waters of a flood. That would also be when He separated His Light from the darkness, the setting up of the place of darkness in the heavenly to be Satan's new home called hell. It was also when God judged and sentenced Satan to death, and giving him the power of death (Heb.2:14).
Heb 12:25-29
25 See that ye refuse not Him That speaketh. For if they escaped not who refused Him That spake on earth, much more shall not we escape, if we turn away from Him That speaketh from heaven:
26 Whose voice then shook the earth: but now He hath promised, saying, "Yet once more I shake not the earth only, but also heaven."
When did God literally shake this earth only? Paul is quoting from Haggai 2:6-7, with Hebrew echad put for "one", which means one of several (unicus in Latin, which means multiple as one. That's why Paul says here, "Yet once more...".) Then Paul gives greater detail as to this future shaking...
27 And this word, "Yet once more", signifieth the removing of those things that are shaken, as of things that are made, that those things which cannot be shaken may remain.
That's the shaking and burning of the "elements" Peter was talking about in 2 Pet. 3. In the Greek it's about man's works on this earth being removed. This future shaking Paul speaks of from Haggai is the great shaking on the day of The LORD at Christ's return, as given in Scripture like Isaiah 2:19; Isaiah 13:13; Joel 3:16; Isaiah 30:32-33; Ezekiel 38:19-23.
"Yet once more" signifies that God also did that degree of shaking of only the earth once before, but when? I believe the first one was to end Satan's rebellion of old. That would be the only comparable level of a previous shaking of this earth that's anywhere close to the final one at Christ's future coming.
Jer 4:23-28
23 I beheld the earth, and, lo, it was without form, and void; and the heavens, and they had no light.
24 I beheld the mountains, and, lo, they trembled, and all the hills moved lightly.
25 I beheld, and, lo, there was no man, and all the birds of the heavens were fled.
26 I beheld, and, lo, the fruitful place was a wilderness, and all the cities thereof were broken down at the presence of the LORD, and by His fierce anger.
27 thus hath the LORD said, The whole land shall be desolate; yet will I not make a full end.
28 For this shall the earth mourn, and the heavens above be black: because I have spoken it, I have purposed it, and will not repent, neither will I turn back from it.
(KJV)
There's that previous shaking of the earth in the degree that Hebrws 12 is speaking of a future final one. That's the link to the event of Genesis 1:2, with the earth having become a waste and an undistinguishable ruin per the Hebrew of "without form, and void".
Does that mean flesh man existed back then? No. Those "cities" point to that beast kingdom structure of ten horns, seven heads, and seven crowns that Satan originally drew a third of the angels to earth with, per Rev.12:3-4. That was about the "all great nations" of that time which dwelt under Satan's branches in God's Garden, per Ezekiel 31. God's Garden of Eden was on earth back then, as we're given that hint even in Genesis 2 with God's River flowing out of Eden to feed four literal rivers on the earth, of which two of those rivers can still be geographically located on earth today (Hiddekel or Tigris, and the Euphrates).
If you don't understand this, then you'll never understand in what time Satan was "perfect in his ways" with following God per Ezekiel 28, and exalted as the high cedar in God's Garden. You won't understand the ancient history of the earth either when God originally created it, and when all the sons of God sang for joy.
God is going to shake this earth once more, like He did of old. And He's going to shake Heaven also, casting out Satan and his host. God Himself is coming back to this earth to reclaim His inheritance of old, The Zion He loves, and His people who love Him through His Son.