It would seem you have not kept up with their production schedules. Yes 223 was done many months ago but Rick has explained time and again their schedule.
I will reiterate for you. 1st run lowers ended with 223, then they started production on F/A uppers, then made more SS uppers while waiting for additional material for lowers to arrive.
Then they start on run 2 and then run 3 lowers then will go back to uppers. So logically several hundred uppers were made in between run 1 of lowers and run 2.
I seriously doubt they are sitting on a bunch of finished lowers waiting for the right day to start shipping them.
I know that some have been shipped in the last few days as I saw the post person with a number of them. I suspect there will be more shipping next week and the next week and so on.