When he began to reign; either,
1. When he began to reign alone, and with full power, or after Jehoahaz's death; till which the people would not disown him whom they had anointed king, which was esteemed a great tie, 2 Samuel 19:10; nor own or accept Jehoiakim as their king, but only as his brother's viceroy, though Pharaoh had by violence forced him upon them. And so Jehoahaz might be his elder brother, and the same who is called Johanan, and is first mentioned, as the eldest son, 1 Chronicles 3:15, though he may be placed first not in regard of his birth, but of his dignity, the crown being first put upon his head. Or,
2. When he was first set up by Pharaoh; and so this was the elder brother, though by popular violence put by his right: See Poole on "2 Kings 23:30".