First of all visa number is already allocated for Oct based on demand.
Secondly E2C has only 2415 cases (USCIS data) distributed in 4/15/2007 to 07
/15/2007 . which is less than 2800, so in any case, the roll back will not
be earlier than July, 2007. But I don't believe it's going to move forward
again, it's highly possible that Cut off date for Dec will roll back to
somewhere 08/2007 to 11/2007,depending on how many people filed I485. This
is just my hypotheses...