early reader vs narrator

early reader

noun
  • Synonym of first reader (beginning book for children) 

narrator

noun
  • One who narrates or tells stories. 

  • The person or the "voice" whose viewpoint is used in telling a story. 

  • The person providing the voice-over in a documentary. 

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