Albert Barnes Commentary Jeremiah 28:3

"Within two full years will I bring again into this place all the vessels of Jehovah`s house, that Nebuchadnezzar king of Babylon took away from this place, and carried to Babylon:" — Jeremiah 28:3 (ASV)

Within two full years - literally, in two more years, even days. Hananiah probably was induced to fix this date by the expectation that the confederacy then underway would defeat Nebuchadnezzar.