Greek has 2 words for “time,” kairos, used here, refers more to the quality of time, and chronos, from which we get chronological, refers more to the quantity. As used here it means the right time.

Jesus had a call on His life and could not publicly display Himself in Jerusalem as the Messiah until the Passover, 6 months hence. (Why not?) The Feast of Tabernacles was not the time for Him to do so.