Just talked to my local Petco manager and she was quite sure the sale wouldn't come until the end of September or beginning of October although I have no clue where she gets her information.
Also said that the sale is "expected" to include up to 55 gallon tanks.
I'm hearing from old coworkers that based on the ad set, its only 20 and 29. And the 55 isn't $1/g. didn't get a date but i think its this sunday...we'll see i guess.