Don't Wait!
My advice as someone who has been working the Fringe Fest for years, is don't wait to see what shows are good or not...by the time reviews come out, you probably won't get a chance to see the best of the best at the festival.
Read the descriptions, pick something that sounds interesting, and take your chances. It's not expensive, so you don't have all that much to lose.
If I can make a couple suggestions (I have NOTHING to do with these shows)
Brilliant Traces @ Factory Studio
YYZ/LAX @ Factory Main
Hip Hop 4 Dumeez @ Poor Alex
A Quiet Place @ Robert Gill
are all shows I've either seen (Hip Hop) or HEARD good things about...
Hope it helps!