One of the bits of information that I gleaned from the 9/11 Commission meetings....that the 9/11 attack was actually planned to occur earlier in the spring/summer of 2001.
The one reason that AQ changed plans to 9/11 was because Senate/Congress was on summer break. So they wanted to make sure that Washington DC was back to work when they attacked.
I am not sure when DC is back to summer break for 2004, but this could help in determining their timeframe....maybe.
You have a point.
Worth exploring...
July 26 - September 6