*** it-2 p. 32 Jeremiah, Book of ***
When Written. For the most part, the book of Jeremiah was not written at the time he declared the prophecies. Rather, Jeremiah evidently did not put any of his proclamations into writing until he was commanded by Jehovah, in the fourth year of King Jehoiakim (625 B.C.E.), to dictate all the words given him by Jehovah to date. This included not only words spoken about Judah in Josiah’s time but also proclamations of judgment on all the nations. (Jer 36:1, 2) The resulting scroll was burned by Jehoiakim when Jehudi read it to him. But Jeremiah was ordered to write it over, which he did through his secretary Baruch, with many additional words.—36:21-23, 28, 32.
The remainder of the book was evidently added later, including the introduction, which mentions the 11th year of Zedekiah (Jer 1:3), other prophecies that Jeremiah wrote down at the time he was to deliver them (30:2; 51:60), and the letter to the exiles in Babylon (29:1). Additionally, the proclamations uttered during the reign of Zedekiah and the accounts of the events after Jerusalem’s fall, down to about 580 B.C.E., were added later. It may be that, although the scroll written by Baruch was the basis for a large part of the book, Jeremiah afterward edited and arranged it when adding later sections.
A few "evidentlys" in there and a "may be".