erstwhile vs precursory

erstwhile

adj
  • Former, previous. 

  • Respected, honourable. 

precursory

adj
  • Being or relating to a precursor; relating to events that will follow. 

noun
  • A precursor; a sign of the onset of something. 

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