already vs hitherto

already

adv
  • Prior to some specified time, either past, present, or future; by this time; previously. 

  • An intensifier used to emphasize impatience or express exasperation. 

  • So soon. 

hitherto

adv
  • Up to this or that time or point. 

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