So Far Meaning

(idiomatic) A limited distance, literal or metaphorical.

Example:   So far, nothing unusual has happened.‎
  How are your driving lessons?  So far, pretty good.‎
  Don't expect a long walk.  You can only go so far in that direction.‎
1915, George A. Birmingham, Gossamer, chapterI:
  As a political system democracy seems to me extraordinarily foolish, but I would not go out of my way to protest against it. My servant is, so far as I am concerned, welcome to as many votes as he can get. I would very gladly make mine over to him if I could.
2013 August 10, Lexington, “Keeping the mighty honest”, The Economist, volume 408, number 8848:
  British journalists shun complete respectability, feeling a duty to be ready to savage the mighty, or rummage through their bins. Elsewhere in Europe, government contracts and subsidies ensure that press barons will only defy the mighty so far.