Brian, 1 September is a holiday. Mail ain't moving then, either (not to say it moves very well the rest of the time). Since 31 August lies in the middle of a long weekend, your call whether to have the actual deadline be before (8/30) or after (9/2). But if you manage to get anything postmarked on 9/1, you and the postmaster (or postmistress) are *awful* friendly.

Joe