So here's the funny thing about taking the bible out of the hands of the Christians and putting it back into the hands of the Jews. You get a more accurate SENSE of what is going on, although dates are someone likely to change. They don't care... what happened happened. But for JWs, life as they know it is DATE SPECIFIC.
THE FALL:
After the Battle of Carchemish in 605, Nebuchadnezzar set his sights on Jerusalem and started a series of sieges after King Jehoiakim stopped paying tribute on year 4 of Nebuchadnessar. This lead to an attack and the death of Jehoiakim on year 7 or Nebuchadnessar. There was a gradual taking over of the city from 597 all the way until 582. The "fall of Jerusalem" is technically around 586 when after King Jehoiakim is dead and his successors are sent into exile and Solomon's temple is destroyed (the fall of an icon like the temple would be a marking point for future generations).
THE RETURN:
SO... enter Cyrus who takes over Babylon in 539 and sometime within his first year he allows the Jews to return to Jerusalem, so between 539 and 538. Now, if you consider how long it took to get the Jews OUT of Jerusalem, you can imagine that it would take less time to get them back IN their dear city... but still take a couple of years, at least... past 537.
With the granting of occupation at one end, and the completion of occupation at the other end... the space in between would be vast. This is made apparent as they didn't start working on the foundation of the second temple until 520.
Contrary to fundamentalist beliefs, there are no specific dates to any events of this magnitude involving millions of people in the B.C. era. So to calculate ANYTHING off such would be denying the very nature of how people worked, moved, fought wars, and recovered from battles in that period of history.
Also " 537 + 70 = 607" is going BACKWARD in time.