on time vs posthaste

on time

adj
  • Punctual or according to schedule. 

prep
  • By installments, payments over a period of time. 

  • By a player's running out of time. 

  • Punctually or according to the schedule. 

posthaste

adv
  • quickly, as fast as someone travelling post; with great speed 

How often have the words on time and posthaste occurred in a corpus of books? (source: Google Ngram Viewer )