@ the-question: if you are a genuine & sincere Bible student, compare the WTBTS's chronology of the Babylonian/Medo-Persian prophecy with the Biblical account.
Fact: Babylon and its king were overthrown in a single night in 539 BCE. If Jerusalem was destroyed by Babylon 70 years earlier, that would give the year of 609 BCE - not 607 BCE.
Fact: In order to force "a square peg into a round hole," the alleged "faithful slave" states that it took the exiled Jews more than a year to return to Jerusalem and begin their rebuilding projects.
These scriptures put the spotlight on the WTBT's corrupt logic of adding on time to prophecies in order to fit their prophetic predictions. (e.g. "overlapping" generations)
(Jeremiah 25:11,12) "And all this land must become a devastated place, an object of astonishment, and these nations will have to serve the king of Babylon seventy years."’ (not 68 years - and then serve the Medo-Persian king for the remaining 18 months) And it must occur that when seventy years have been fulfilled (not 68 years) I shall call to account against the king of Babylon and against that nation,’ is the utterance of Jehovah, ‘their error,..."
(Jeremiah 29:10) "For this is what Jehovah has said, ‘In accord with the fulfilling of seventy years (not 68 years) at Babylon I shall turn my attention to YOU people,..."
(Zechariah 7:5) "Say to all the people of the land and to the priests, ‘When YOU fasted and there was a wailing in the fifth month and in the seventh month, and this for seventy years,.." (were they wailing for 68 or 70 years?)
The org's sums don't add up.