See my post at 12 regarding "anthrax attack AFTER 9/11".
We've got al-Haznawi with a lesion in June. (These guys are pretty good if they didn't panic and get rid of it all then.) We've got deaths in October and November. It seems to me some of this got mailed after 9/11.
If they were trying for simultaneous action, they would have known the mail wasn't the way to go.