first night vs unveiling

first night

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

  • The first night after marriage. 

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

unveiling

noun
  • The act of unveiling or uncovering. 

  • A ceremony for the first public showing of something. 

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