1. The matter of the zero year was simply a matter of methodology and when it was realized that there was an error then an adjustment was made. This is no big deal because chronology is a science that has always been in a state of flux. Suh fine tuning did not impact on the validity of the 1914 CE date for the end of the Gentile Times, thanks be to Providence.
The methodology was to count back 2520 years from 1914 and choose whicheverdate it hit as the "point of origin". The absence of year zero was the only thing that changed the "point of origin" from 606 to 607, there wasn't any fundamental difference in the way the dates were calculated. This type of chronology is simple, it involves simple addition and subtraction.
It is blatently obvious that if year zero were not the issue, then 1914 would have been modified to 1913. It is so very simple that only someone who is metaphorically blindfolded can fail to notice it.
2. Accoding to accurate Bible chronology Josiah died in 629 BCE so you are twenty years wide off the mark.
Your opinion of "accurate bible chronology" disagrees with every piece of archaeological evidence from multiple sources. Even if you thought the Babylonian sources were somehow tainted, incorrect or outright fabrications, the corroborating evidence from Babylon's biggest enemies Egypt, Assyria and Persia should have convinced you. It is only your stubborn, one-sided attitude that prevents you from admitting it. I guess your blind faith in the Bible as the inerrant word of God is the barrier to your seeing the logic and mountains of evidence that prove the "exile" was not 70 years.
3. Biblical evidence begins Neb's reign in 624 BCE so once again you are twenty years off the mark.
See above.
4. 537 BCE is not guesswork but a defined date calculated with the secular and biblical evidence if you have a better date then please put it up. No one suggests that the trek back to Jerusalem took two years but rather 4 months would be reasonable depending on what route the exiles took.
What is the secular (or for that matter biblical) evidence that the rebuilding took place in 537? (This question is important, please don't ignore it).
Nobody can give a solid date for the rebuilding because there is no evidence for any of the dates. It is far more honest to say "I don't know" than to invent a date based on an assumption and then blindly believe it.
5. To say that 607 BCE has no support is simply stupid because there is clear evidence both from the Bible, Josephus and NB chronology to support such a determination. With the latter its records brings us within a twenty years striking distance and when the seventy years is factored into that chronology then Bingo you have a rock solid, irrefutable 607 BCE.
Show me such evidence then. Where in Josephus' works is 607 supported? 537 and 607 are both pure speculation and guesswork. 539 is the only supported date in that period and the chronology works perfectly until you try to squeeze 607 into it. You get a "phantom" 20 years poppng up that throws out all the calculations of the dates for the famous battles between the major powers in that region. Every thng fits into place until you try to say Jerusalem was pillaged in 607 because we know exactly where all the main protagonists were and what they were doing in that year. It just doesn't work.
Even the Watchtower's own literature doesn't support 607 as being the 18th year of Nebuchadnezzar's reign. If the Watchtower itself doesn't support itself how on earth can you have a "rock solid, irrefutable 607"?
6. Apostates have a hang-up over the zero year problem but fine tuning and correct methoidology proved the validity of 1914 CE.
Year zero is more than just a matter of fine-tuning. You act as if archaeologists and historians didn't know there was no year zero. These historians had more or less worked out Babylonian chronology long before the JWs stuck their oar in. The fine-tuning was already done, the JWs just bent the evidence to fit their own beliefs, simple.