Doug and others,
This is how the "70 weeks" is interpreted by some, which obligates none to accept it but...
It is clear that the "messiah" would appear after 69 weeks, thus after 483 years. So many, including JWs, consider the messiah as appearing at his baptism in 29 CE. So they just make a simple calculation.
483 - 29 = 454 BCE + 1 (no zero Roman year) = 455 BCE
So JW doctrine is fundamental that the 70 weeks begin in 455 BCE.
The only difference is that they used 529 BCE as a "pivotal date" for the fall of Babylon, though they ignore all other secular dates. Problem is, when the timeline was revised, this included the date for the fall of Babylon. So 529 BCE is a revised date for that event.
Once realizing that, others have concluded that the initial reference to the "going forth of the word to rebuild Jerusalem" must have been a reference to the rebuilding in the 1st of Cyrus, forcing us to date the 1st of Cyrus to 455 BCE.
This means that there is a whallopping 82-year difference between 537 BCE and 455 BCE for the return from Babylon. But once we look at how empty and incompetent the Persian Period is, it is quite easy to remove these extra 82 years. Watch!
Remove 30 years from Darius I, making his 36 years 6 years, which is confirmed by the Bible.
Also remove the extra 30 years from Artaxerxes II, so that his 47 years becomes 17 years. Ctesias claims he was physician for Artaxerxes II for precisely 17 years! That is 60 years right there!
Then when we find out Xerxes and Artaxerxes were the same king, that removes another 21 years for his separate reign.
See? We're done! That's 81 years removed right there! Easy. Simple. Quick.
When the true date for the 1st of Cyrus is 455 BCE, though, and we follow Josephus and the Bible which begins the 70 years of desolation starting with the last deportation, then year 23 of Neb2 falls in 525 BCE and year 19 in 529 BCE. That re-dates the 2nd coming from 1914 (607 BCE) to 1992. Of course, as noted, 1992 has to be the 2nd coming date because it fulfills 1335 days, or 45 years after 1947, which ends the 1290 days, the year the Jews come out of exile and get their self-ruled country back.
The confirmation from heaven of all this is the "sign of th son of man" which did begin to appear to the elect with the birth of the messiah in 1950, and is shown by the WTS in the Revelation Book in 1988, that is, the sign of the sleeping black child is shown in the palm of Jesus Christ. The actual sign that appeared was of sleeping black child, meaning the messiah was the black prodigal son.
Jesus has to return in the flesh, only the second time, not having access to his own body again, he uses the body of the prodigal son. That is why the second wave offering is described WITH LEAVEN, meaning with sin, proving Christ at the second coming would be hiding out in an imperfect body. The first wave offering is without leaven and celebrates the UNLEAVENED BREAD, which represents Christ's sinless body at the first coming.
Christ fulfills the FIRSTFRUITS of both wave offerings, only they are different. One has leaven, the other doesn't. The SECOND is the one WITH the leaven, so the elect expect Christ would return in the flesh in an imperfect body. It just so happens it's a black person (i.e. Ethiopian eunuch) so when the sign of the son of man appears, it uses black clouds to represent the black skin of the prodigal son messiah chosen as the new body of the messiah at the second coming.
That's what's going on. Right now you can see a photo of the sign taken in 19