‘In the fifth day of the month, which was the fifth year of king Jehoiachin's captivity, the word of Yahweh came expressly to Ezekiel the priest, the son of Buzi, in the land of the Chaldeans by the River Chebar, and the hand of Yahweh was on him there.'
The captivity of Jehoiachin can be precisely dated on the basis of the Babylonian Chronicle tablets to March 597 BC, thus this would be in 592 BC.
The change to the third person does not necessarily indicate different authorship. Having commenced on a personal note, Ezekiel may well now be incorporating an official introduction in the third person to authenticate the book and reveal its authorship. This is especially so as the dating here does not stand by itself but requires Ezekiel 1:1 to tell us that it was the fourth month. (It is quite possible, however, that he may have used a scribe).
The introduction affirms the work to be that of Ezekiel the priest, the son of Buzi (see also Ezekiel 24:24). But what was more significant was that ‘the word of Yahweh' came to him ‘in the land of the Chaldeans' (that is Babylonia). God was not limited by boundaries or location. Note here that central to the visions was the coming of ‘the word of Yahweh'. God had given the visions so as to speak and act among His people.
‘And the hand of Yahweh was on him there.' Nor was there a limit on His actions. For Ezekiel was not only aware of the word of Yahweh, but he experienced the hand of Yahweh. Indeed wherever His word comes His hand acts, to protect, to strengthen, to guide and to restore. Compare Elijah in 1 Kings 18:46 and Isaiah in Isaiah 8:11. See also Isaiah 25:10; Isaiah 41:10; Isaiah 41:20). But in Ezekiel the working of ‘the hand of Yahweh' is seen in vivid ways (Ezekiel 3:14; Ezekiel 3:22; Ezekiel 8:1; Ezekiel 33:22; Ezekiel 37:1; Ezekiel 40:1).