This President's Scholar and SAFOS, was a Colonel, on June 24, 2017, when he was appointed as Commander of 6 Division, taking over from BG Chua Boon Keat.
Between June 24, 2017 and Jan 01, 2019, he rose from Colonel to MG.
Assuming that he was promoted to BG on July 01, 2017, within 1.5 years...