I walked up to the window 20 minutes before a Sunday matinee back in March and was given a seat in the 9th row of the center orchestra. Granted, the theater was somewhat empty, and it might be more crowded since it's the summer, but you should be still able to get it.
Just know that the rush tix are $35 and not $25.
-There's the muddle in the middle. There's the puddle where the poodle did the piddle."