At exactly the arranged time (2,3,3)
I believe the answer is:
on the dot
'at exactly the arranged time' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for on the dot that I've seen before include "Precisely punctual" , "At exactly the right time" , "Promptly" , "at exactly the arranged time" , "Absolutely punctual" .)