When did Nebuchadnezzar first come against Jerusalem?
Nebuchadnezzar first came against Jerusalem in 606 B.C. The context notes this was his first incursion, and then 70 years later the Jews were permitted to return and begin rebuilding the temple, with 42,360 returning under Cyrus's decree. This marked the start of the seventy-year period before their return.
Les explains that Nebuchadnezzar came over the first time in 606 B.C. Then 70 years later, the Jews were permitted to come back and begin to rebuild the temple. This return is associated with Cyrus's decree, and about 535 or 536 B.C. 42,360 Jews took up the offer to go back to Jerusalem, even though it was a wilderness and barren. Les notes that although it would take hard work, it was still home.