Greetings!
Your conclusion is sort of correct but the reasoning is not quite accurate. One person has already pointed out the reference to the s"ervice to Babylon" being 70 years and this can have reference to the Jewish state's subjugation of political and military power to Bablylon which occurred long before 587 BCE, and actually, even before 607 BCE..
To that person's point, I would point out that the terms that have been translated as "desolated" are more properly understood as the etymology suggests. That is to say that "desolation" means to "de-soul" some place or in other words to remove the people from the place.
The Babylonian and Jewish histories indicate that about 609-606 BCE, the babylonian armies had already pretty much subdued all of the surrounding countryside, and pretty much had Jerusalem itself bottled up. Persons, especially nobles and members of the upper class, like Daniel were even taken captive and sent to Babylon years before the actual razing of the temple. Thus it could be said that land and even Jerusalem, as it represents the Jewish seat of power, commenced its desolation long before that event.
(Keep in mind too that the land was NEVER completely desolate in the sense that not a single person was around for the Babylonians left certain vinedressers and even imported a few people that lived on the land), though of course wiht LESS people around, some of the "wildness" and beasts were able to have a little bit more freedom to roam around.
Finally, a third consideration is that the "70 years" is probably not meant to be taken literally but rather more generally refers to the approximation of a "generation" so that Jeremiah and other prophets who make reference to the babylonian captivity lasting for 70 years really mean that it was to last "for about one generation" of persons. Basically persons going off to Bablylon were told not to plan on coming back themselves but were promised that their children would be restored.
Of course any or all of these three alternative reasonings BOTH support a prophetic truth viewpoint to the scriptures and at the same time do not conflict with the actual date of the "destruction of Jerusalem" and burning of the Temple which practically every authority, record and scholar, other than JWs, agree occurred in 587 BCE.
Of course, JWs, for the time being cling to the idea that the 70 years must be literal because the whole Gentile Times (theory) doctrine is based upon similar literal understanding and interpretation.
-Eduardo