That's a good analysis. I first thought you said Jo finished IBH on March 12th and I was like "Why she can't finish this one on March", but then I reread haha
What are the chances though that she finished the other ones with enough padding time (is that the right expression) and the publisher decided to release it on August/September but could have done it before if they wanted? As in the 9-month delay is not needed, and the manusript can be delivered a bit later.
The chances aren't good. Speaking from personal experience, a traditional print run will take about 4-5 months from the point they're shipped to the printer. (I wanted to tweak my Dumbledore book a little at beginning of June 2021, my publisher said it was already shipped to the printers by then for a mid-October publication date.) That's time for the books to be printed, bound, shipped, reviewed, etc. Allowing for the fact that Strike books will have print runs well into the six figures, if not in the millions (source: https://www.thebookseller.com/news/newsrowlings-troubled-blood-sells-more-day-lethal-white-week-1219476), and that they are insanely long... err on a longer printing time than a shorter one. So if a publisher wants the book ready to go by November, it needs to be sent to the printers by June at the very latest, and most probably May.
Working backwards from there. You need time for formatting and copy edits (moving commas around, etc.). Consider that the book is 1000 pages, so that is easily a month if rushing, maybe two. So now we are in April at the latest, preferably March.
Next is the question of editing. I think it's safe to say that Jo's Strike books are barely being edited by any publisher these days - if they were, that adds at least two months for a book of that length. Even if the publisher isn't really interfering with the manuscript, Jo herself will be editing it - when she announces "Done!" that's for a first draft. She's meticulous, and will go over the manuscript at least once or twice before it's ready to go (possibly many more times!). So either way, block off two months at a minimum for editing after Jo says "Done!" And that gets us right back to January/February.
So as astonishing as it is to people outside publishing, there really is no cushion or padding in a 9-month stretch from "finished draft" to "published book." If everyone REALLY wanted it, working around the clock and cutting corners where possible, maaaaybe you could get it done in 7ish months, but it doesn't seem to be the case - not like you need to "strike while the iron is hot" for books by Jo Rowling, the fanbase will be there. So barring a miracle in Jo's writing pace over the next month and a half, I don't think it's happening for 2023.