by and by vs earlier

by and by

adv

  • After a short time. 

  • After an indefinite period. 

noun

  • Heaven; the hereafter. Usually preceded with "the sweet." 

earlier

adv

  • previously; before now; sooner 

adj

  • occurring previously 

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