Mentioned to Tuna on another thread that my earliest- on occasion -is sometime in the third week of August-  a whole fistfull of variables qualify that time though and it's certainly NOT dependable year to year. IMHO.
  Because of past seasons though its when I really start to get out there and look and cast to deeper holes with a bit of anticipation. Start generally in earlier August down low but only expect an odd Smallmouth or two to hit that early.
 Dont bet the Farm on that time or make special trips as your far more likely to be disapointed than rewarded- at least with a fish.