My wife's and my passports with visas arrived today 14 December in San Diego. Our trip begins in four days on 18 December, traveling to Thailand for three weeks before going to Myanmar in January.
We sent them to the DC embassy from Maui, on 21 November (right before Thanksgiving) after returning from foreign travel.
They arrived at the embassy on 26 November and were sent back on 12 December. The effective visa date is 10 December.
23 days total with FedEx 2Day. The shipment to the embassy took longer because of Thanksgiving. Seems like it would have been a 3 week turnaround without that.
As mentioned, we were traveling outside the country, and had a 28 day window to get the visas. Too close for comfort, and as more people travel to Myanmar, it will surely take longer.