Okay.
Believe me I do not consider myself competent in calendrical issues, nor do I hold to a young earth theory.
Here goes:
Orthodox Jews calculate the birth of Abraham at 1948 years after the creation of Adam.
If we guess-timate from Abraham to Jesus is about 2000 years,
then we have about 4,000 years from Adam's creation to Jesus. That puts the creation of Adam to about 6,000 years ago, or about 4,000 BC.
Orthodox Jews calculate 987 years from the creation of Adam to the translation of Enoch.
If Enoch wrote his books during the year before his translation (as I think is indicated by the Book of Enoch) we should deduct 986 years from about 6,000 to calculate the date for the writing of the Books of Enoch, which is bout 3,000 BC, give or take a century or two. ;-)
BTW, Orthodox Judaism dates the death of Methuselah to 1656 years after the creation of Adam, the year of the flood of Noah's day. That makes the flood to have happened about 2,300 years B.C.
Bear in mind certain caveats:
1. I do not believe the earth is young, or 6,000 years old, even if the creation of Adam is from about 6,000 years ago
2. I don't even believe in the calcualtions I have here because:
- I think the calendars have changed enough over time to make this exercise problemaitc
- I am terrible at math and you may have be able to detect errors in my adding and subtracting here.
- I don't think the age of the Book of Enoch is critical, there are enough ways for God to have preserved it for it to be so.
3. I believe Enoch wrote it.