Meaning:

Things have been going well until now.

If you say "So far so good," you mean everything has been happening successfully up to now.
This expression is used often when you there might have a problem soon.

How are your final exams?
So far so good, but I have two more tests tomorrow. They are the most difficult ones.

I got up early, dressed warmly, and arrived at the stadium 15 minutes before the game.
So far so good -- then I realized I left the tickets at home.

Twitter