Saturday, September 10
Labor Day is Monday of that week (Sept. 5), so please take that into account. Given that USPS does "average" transit times rather than guaranteed ones, it's probably better to have it arrive a week ahead of time than to try to time it too closely. Frenchy lives closest to me, and she's about an hour away, so if we miss the date I'll end up having to re-ship, and I really really don't want to do that.
If you need until the end of next week to harvest & pack, please consider sending UPS instead of USPS. I don't think the semps will be especially heavy, so shipping rates shouldn't be too much more (I just did a quick check putting in 10 pounds as the weight and got $25). UPS still needs 5 business days (mail on Friday to arrive the following Friday) from Oregon to Maryland, but it's a guaranteed 5 days, not a hopeful approximation.