Answer from fanatic JW mother on this very topic is: the FINAL and complete destruction of Jerusalem was 586/587, possibly, yes. But the destruction of Jerusalem actually BEGAN in 607 BCE and that's what count's ISN'T IT!
Marjorie (Alleymom) deserves a lot of credit for that KISS approach. It is as sleek as I believe the thing can get, nearly a work of art in its elegance.
It is still too scholarly for most of the JWs I know.