We Jews don't have an exact date for when a lot of these "sure dates" Jehovah's Witnesses claim. In fact, if you note their materials they almost always ignore Jewish history and go straight to saying something like "secular historians claim..." In all honesty, the secular numbers don't always match up with our numbers, but they are far closer.
To illustrate: Some traditional rabbinical sources date the completion of the first Second Temple edifice as early as of 3408 A.M. (350 B.C.E.) but the best Jewish history and critical estimates have the Temple completed around 3574 A.M. or about 515 B.C.E. on the Gregorian calendar.
Even within the 166-year discrepancy, the Jehovah's Witnesses' 607 chronology has us not even returning to Jerusalem until 3596 A.M. (537 B.C.E.), more than 20 years AFTER the latest date for the Second Temple's dedication date. This makes the Watchtower calculations impossible.
I'll bet almost none of you knew the A.M. dates, right? Why not?
Because all that JWs are ever exposed to in Watchtower publications is the JW calculations and the secular data they choose. Ever hear of a "straw man ruse"? This is when a debator invents or fabricates a problem in order to trick people into believing he has the solution. Since he made up the original problem, he can also easily tackle it since it is fabricated to begin with. Like a man made out of straw, a fabricated controversy is easily solved by the liar who makes it up.
This is the whole 607 B.C.E. debate in a nutshell--a cheap trick. All one had to do was check the Jewish date that the Second Temple's pre-Herodian edifice was completed, either the traditional date or the secular one or any in between--and count backward from there. May not get precisely matching dates, but close enough to agree with secular experts for the fall of Jerusalem.
But the Witnesses don't mention the A.M. dates because then they cannot control the parameters of the argument...
...And that's what you want when you present a straw man as your argument.