about time vs momentarily

about time

adv
  • Close to the right time. 

  • Far past the desired time. 

  • Used other than figuratively or idiomatically: see about, time. 

momentarily

adv
  • In a moment or very soon; any minute now, any time now. 

  • In a momentary manner; for a moment or instant. 

  • Progressively; moment by moment. 

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