first night vs lead-in

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. 

lead-in

noun
  • An introduction; something that leads into the beginning of something. 

  • A short phrase that begins the caption of a photograph. 

  • A region of data at the beginning of a compact disc, holding the table of contents. 

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