First in the nation by our measure: Kentucky.
Law requires their absentee ballots be printed by 9/15, and the state tells us that they mail as soon as the envelopes are stuffed.
The Federal deadline for UOCAVA ballots to be mailed is 9/20, so about 6 million ballots will be sent out that date.
Then there is a pile of states who have a 45 day window: ID, VA, DE, AL, MA.