Why should I-140s filed before August 1?
There two considerations: One is about priority date, and the other is about the procedure. We are talking about the Visa Bulletin for July, 2007. Your I-140 application must be filed in July, 2007 to kick in the extended benefit to file I-485 before August 18 to take advantage of the extension. Otherwise, you cannot submit your I-485 on or after August 1st at all as you do not have a priority date that satisfies the July visa bulletin. Even if your case is based on labor certification, the filing procedure requires you to file I-140 before August 1. If your I-140 is filed after July, there is no legal base for you to file the I-485 application to use the July visa bulletin. However, if your case is based on labor certification, the you may file I-140 and I-485 after August 1, but before August 18, according to USCIS interpretation.