If you actually go to the Amazon web site to order the book, they (as of Thursday night) say it “usually ships in two to four weeks”.
If you order a book directly from Matt you will probably get a postcard in the mail instructing on how to order the next book in advance!
Amazon has no humans working there. It’s the borg. Totally automated, run by Tandy TRS-80 computers.
Once the 75 books arrive in a day or two, the website will automatically switch to saying the books are immediately available. No human will make this change or care. Amazon is just a vast Pentagon sized building staffed by robots and run by computers.