heretofore vs thenceforward

heretofore

adv
  • Before now, until now, up to the present time; from the beginning to this point. 

  • Previously within the present text; earlier herein. 

thenceforward

adv
  • from then on; from that time on 

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