I got first Moderna today in Arlington at the ESports center and I don't think it could have gone more smoothly considering the volume of people they are dealing with.
10-15 mins in car line which was four lanes for 2p-4p appointment window. They stop you and make sure your name is on the list and direct you to the parking lot. Short walk to the building where you go in, get a temp check and enter a pretty lengthy line that wraps around a few halls. Lengthy in terms of space not time - it moved constantly and was prob no more than 5-10 mins. While you're in that line they are directing you to scan the bar code on your ticket which takes you to a website where you check in, answer health questions, acknowledgements, etc. This is the part I could definitely see a lot of seniors struggling with. I am pretty tech savvy and barely finished the online form while walking by the time I got to the front. But they are well prepared for that too and will fork the line of people needing more time or assistance off to the left where staff are waiting to help, or off to the right if you've completed yours and show them the green "clear" message on your phone.
Next your are moved to a waiting area which is about 8 rows of 20 chairs spread out. I sat there for probably 5-10 mins and they call you by the row. From there you are directed to one of 20 or so stations around the room, each with a person handling the details and two spots on either side of the table with the folks administering the injections.
All in I was there for a little over an hour counting time in car line. I'm sure it's not perfect but this has to be one is the early hub models to follow I would think.
Ps. I am a McKinney resident and it does not matter. Thankful to Tarrant County and the Arlington PD and FD.