Make it easy for them. The JW mind is not accustomed to analyze. Here is some information regarding what the Watchtower has printed in regards to the Babylonian kings and how the lengths of their reigns can be calculated to arrive at the date of the destruction of Jerusalem by Nebuchadnezzar. If you're a dunderhead on Neo-Babylonian history (like me) you've probably remained totally clueless whenever the subject of the chronology leading to back 607 B.C. as the date for the destruction of Jerusalem by Nebuchadnezzar comes up. It turns out this stuff is a piece of cake! Using ONLY comments by the Watchtower Society and one scripture we can rather easily see their chronology regarding the destruction of Jerusalem. There is really not much to learn here, either: No astronomy, no neo-Babylonian tablets, and no confusing Bible versus will be presented. Just the names of five people and several quotes from Watchtower publications will be used. Also, there is no need to quibble over things like regnal years, ascension years, cardinal and ordinal numbers, etc. Remember, 607 B.C. is a full 20 years earlier than the accepted date of 586/87 B.C. and all the tinkering with a few months here and few partial year reigns there cannot make up a difference of twenty years. Another tricky part to remember is that in order to calculate dates we have to count BACKWARD as you go forward when dealing with time before Christ came to earth. We have to start AFTER the date of Jerusalem's fall with a date and event that is agreed upon by both the WTS and secular historians. From this date we will count backward by counting forward. That date is 539 B.C., the date that Babylon fell to Cyrus the Mede. Keep in mind we are trying to find the date Jerusalem fell.
Insight on the Scriptures published by the Watchtower Bible and Tract Society in volume 1 on page 425 under "Chaldea" has a complete list of the Babylonian kings from Nabopolassar to
Balshazzar:
"Particularly was this domination manifest during the seventh and sixth centuries B.C.E. when Nabopolassar, a native of Chaldea, and his successors, Nebuchadnezzar II, Evil-merodach (Awil-Marduk), Neriglissar, Labashi-Marduk, Nabonidus, and Belshazzar, ruled the Third World Power, Babylon."
_______________________________________________________
Insight on the Scriptures published by the Watchtower Bible and Tract Society in volume 2 on page 480 under "Nebuchadnezzar" tells us that he ruled as king for 43 years:
Second ruler of the Neo-Babylonian Empire; son of Nabopolassar and father of Awil-Marduk (Evil-merodach), who succeeded him to the throne. Nebuchadnezzar ruled as king for 43 years...
_______________________________________________________
An article entitled, "The Rejoicing of the Wicked Is Short-lived" on page 29 in the January 1,1965 Watchtower magazine lists the regnal years of Nebuchadnezzar II's successors from Evil-Merodach to Nabonidus who, in this article the Watchtower confirms was ruler of Babylon when Cyrus conquered it in 539 B.C.:
Evil-merodach reigned two years and was murdered by his brother-in-law Neriglissar, who reigned for four years, which time he spent mainly in building operations. His underage son Labashi-Marduk, a vicious boy, succeeded him, and was assassinated within nine months. Nabonidus, who had served as governor of Babylon and who had been Nebuchadnezzar’s favorite son-in-law, took the throne and had a fairly glorious reign until Babylon fell in 539 B.C.E.
_______________________________________________________
Let's summarize (remember we have to go backwards starting in 539
B.C. with Nabonidus):
Nabonidus ruled Babylon until it fell in 539 B.C. to Cyrus.
Labashi-Marduk ruled for 9 months.
Neriglissar ruled for 4 years.
Evil-Merodach ruled for 2 years.
Nebuchadnezzer ruled for 43 years.
17 years + 9 months + 4 years + 2 years + 43 years = 66 to 67 years.
Starting at 539 B.C. and going back 66/67 years we arrive at 605/606 B.C. for the start of the reign of Nebuchadnezzer.
2nd Kings 25:8-10 tells us that Jerusalem was destroyed in the 19th year of Nebuchadnezzer's reign, so if we go forward 19 years from 605/606 B.C. we will have the approximate years of the destruction of Jerusalem.
Nineteen years after 605/606 B.C. brings us to 586/587 B.C. which agrees with all secular evidence.