earlier vs precursory

earlier

adj

  • occurring previously 

adv

  • previously; before now; sooner 

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 earlier and precursory occurred in a corpus of books? (source: Google Ngram Viewer )