Lehi and his group had been warned by the Lord to flee from the land of Jerusalem so that they would escape this destruction. Most biblical scholars date the destruction of Jerusalem by the Babylonians somewhere between 586 B.C. and 590 B.C. Thus in his chronological footnotes in this section of the Book of Mormon, Brother [James E.] Talmage suggests that the events following Lehi’s vision of the destruction of Jerusalem took place sometime after about 588 B.C.
(Daniel H. Ludlow, A Companion to Your Study of the Book of Mormon, pp. 124)