CVS is accepting appointments for Moderna 2023/2024 this week
@Tom, I believe the availability is based (at least to some extent) on location. Here (Seattle area), I've looked at many places to get the new vaccine, and none have appointments listed as available until Monday. Starting Monday, they all seem to.
I believe Moderna manufactures their COVID vaccines in Bloomington, Indiana - just down the road from you. Out here on the distant Pacific shores, I suspect they are allowing a couple more days for shipping and distribution.
I had been watching all the local options for a few weeks, and had been planning to do the same as you: I figured I'd just make an appointment for around 9/18, and I assumed they would give the "newest" vaccine available at the time (9/18 was my guess weeks ago for availability based on scheduled/expected FDA and CDC meetings to greenlight it, as reported in many news sources). But I noticed something odd: weeks ago, one could schedule a COVID vaccine appointment multiple weeks ahead (don't recall exactly, but I think the booking window was roughly 3-4 weeks). Then I noticed that the window was shrinking with each passing day, and there were no appointments beyond 9/17.
I called and spoke with the pharmacist at several local CVS outlets this morning, and all told me the same thing: they did not have any of the new vaccines yet (nothing in local storage) and they had no idea when they would get them, most guessed end-of-the-month or later. Then around noon today (Pacific) CVS's scheduler web page went offline for 2 hours. When it came back, there were no longer any COVID appointments available this week, through Sunday (there had been many previously). Now, all appointments were 9/18 or later. So it looks like once the FDA approved today, they yanked all existing appointments and started scheduling only the updated vaccine, when it's expected (later this week for folks closer, and Monday for those of us out west), YMMV.
Monday is OK with me, I got the (new) RSV vaccine about a week ago, my sore arm should be ready for another poke by Monday.