Within two full years - literally, In yet two years even days. Hananiah probably was induced to fix this date by the expectation that the confederacy then on foot would defeat Nebuchadnezzar.
Related Commentaries of Jeremiah 28:3
Jeremiah 28:3
3 Within two full years will I bring again into this place all the vessels of the LORD'S house, that Nebuchadnezzar king of Babylon took away from this place, and carried them to Babylon: