inaugural vs preparatory

inaugural

adj
  • Marking the beginning of an operation, venture, etc. 

  • Of inauguration; as in a speech or lecture by the person being inaugurated. 

noun
  • An inauguration; a formal beginning. 

  • A formal speech given at the beginning of an office. 

preparatory

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

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