“on time” -> exactly at the correct time, punctually.
This phrase is used to describe something that arrives, happens, or is done when it should and is not late.
We managed to get there on time.
I want to emphasize the need to get this done on time.
As far as I know, he’s never come on time.
All students are required to be on time for class.
My only worry right now is getting to the airport on time.