I just wanted to draw your attention to a comment Peacefulpete made in this thread.
this only illustrates the problem of attempting to interpret scripture using other scriptures written by men who themselves are only interpreting the earlier ones.
The seventy years prophecy of Jeremiah is spoken of in 2 Chronicles 36:20-23 and Daniel 9:1-2. The chronicler views this prophecy as being fullfilled in 539 BC when the "royalty of Persia began to reign", and the 70 years of Babylonian domination was over.
The prayer of Daniel in chapter 9 during the supposed first year of Darius the Mede shows that the writer thought the seventy years had already ended. That's why he is asking God not to delay the return of the exiles any longer. So again this writer is saying the 70 years had already ended by 539/538 BC. Unfortunately what God actually replies is something like "Did I say 70 years? What I meant to say was 70 weeks of years". So the writer of Daniel 9 is actually rejecting any fullfillment of the seventy years until a time long into the future (which is a give away as to when this chapter was actually written).
The writer of Zechariah 7 seems to be talking of yet a different 70 years, that ended in the fourth year od Darius I, or 518 BC. If the seventieth year of fasting and wailing for Jerusalem ended in 518 BC then they must have begun in 587 BC.
So it appears that these 3 bible writers disagree with the Watchtower society on the interpretation of the seventy years.
You also have the possibility that "seventy years" simply refers to a lifetime as at Isaiah 23:15 and Psalms 90:10, and does not mean an exact number of years.
And as Peacefulpete stated, there are examples of writings outside of the bible where 70 year periods of desolation are prophecied e.g. Marduk's 70 year desolation of Babylon, which is evidence that the 70 years was a standard period of desolation.