The following is From Antiquities of the Jews by Josephus. Here we see that Josephus is well aware that Nebuchadnezzar had an accession year or zeroth year.
1. NOW in the fourth year of the reign of Jehoiakim, one whose name was Nebuchadnezzar took the government over the Babylonians, who at the same time went up with a great army to the city Carchemish, which was at Euphrates, upon a resolution he had taken to fight with Neco king of Egypt, under whom all Syria then was. And when Neco understood the intention of the king of Babylon, and that this expedition was made against him, he did not despise his attempt, but made haste with a great band of men to Euphrates to defend himself from Nebuchadnezzar; and when they had joined battle, he was beaten, and lost many ten thousands [of his soldiers] in the battle. So the king of Babylon passed over Euphrates, and took all Syria, as far as Pelusium, excepting Judea. But when Nebuchadnezzar had already reigned four years, which was the eighth of Jehoiakim's government over the Hebrews, the king of Babylon made an expedition with mighty forces against the Jews, and required tribute of Jehoiakim, and threatened upon his refusal to make war against him. He was aftrighted at his threatening, and bought his peace with money, and brought the tribute he was ordered to bring for three years
My question is: Did Zedekiah have a zeroth year as well?