first night vs vernissage

first night

noun
  • The first public performance of a play or other show, normally assumed to be held in the evening. 

  • The first night after marriage. 

  • Used other than figuratively or idiomatically: see first, night. 

vernissage

noun
  • A private viewing of an art exhibition before it opens to the public. 

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