precursory vs preparatory

precursory

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

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

preparatory

adj
  • Of or pertaining to preparation, having the purpose of making something or someone ready, preparative. 

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