Thanks Ann, I had forgotten about poor old Gedaliah, despite keeping this excellent post from Doug Mason :
" The WTS do not start their Seventy Years with the destruction of Jerusalem. That is a distraction. The WTS start the Seventy Years with the exodus of Jews into Egypt, following the murder of Governor Gedaliah. This is the event that they date at 607 BCE.
The WTS completely ignores the fact that the Bible does not say these Jews went into Egypt in the same year that Jerusalem was destroyed. Indeed, it is impossible for all of the events that took place during the period from Jerusalem’s destruction until those Jews went into Egypt to have been completed within 2 months. It is more probable the Jews entered Egypt 4 years after Jerusalem was destroyed, linking that uprising against Gedaliah to Nebuchadnezzar returning and taking more captives from the land during his 23rd year.
While it focuses on the 539 BCE date for the Fall of Babylon, the WTS’s critical date is 537 BCE for the assembling of the first Exiles at the temple site at Jerusalem. There is no Biblical or other information to prove this date is correct. For that reason, scholars provide alternate dates, but no one really knows. It’s a subjective guess.
Likewise with 1914 CE. The WTS makes a lot of noise and fuss about its views on 1914 CE but the critical date for them is 1919 CE when, according to the WTS, God anointed them as his sole voice upon earth, the true representative of God’s kingdom, his government. That, once again, is a purely a subjective opinion."