When lucifer fell from heaven there was great destruction. Jeremiah 4:23-28 describes the chaos and destruction that occurred. So the exact age of the earth is unknown, and an old earth does not contradict the bible. In Genesis God created man, replenished the earth and made things right again. Note that as a result of this event the heavens were dark and there was no life remaining, unlike the Noah flood where Noah, his family and the animals on the Arc survived:
Jeremiah 4:23-28 -
“I beheld the earth, and, lo, it was without form, and void; and the heavens, and they had no light. I beheld the mountains, and, lo, they trembled, and all the hills moved lightly. I beheld, and, lo, there was no man, and all the birds of the heavens were fled. 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. For thus hath the LORD said, The whole land shall be desolate; yet will I not make a full end. 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.”
Taking Jer 4 23-28 out of it's context is no proof at all. Read ALL of Jer 4 and tell me where you get the idea to peel 23-28 out of it's place in the chapter...