hereafter vs thenceforth

hereafter

adv
  • From now on. 

  • Sequentially after this point (in time, in the writing constituting a document, in the movement along a path, etc.) 

noun
  • A future existence or state. 

  • Existence after death. 

thenceforth

adv
  • From that time on. 

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