The Alex Ross signing hasn't occurred yet so I am assuming that it will still take a while after he has signed your book.
Which was the one you got back? I'm betting the ones you didn't get back were from the Miller / Janson signing which likely was a large group submission - which was approx two weeks ago. It usually takes a month (in my experience) from the date of the signing, and grading and then getting the book back. In other words, if the signing was on June 1, 2023, then I would expect the book back approx on July 1, 2023. Give or take. Hope that helps.