Movies are often based on books. But when was the first time when a book was published about a movie? Example : a book was published about the Indian movie Sholay. Now this book is about the making of movie, but in my question the movies might not necessarily be so. But of course, movie should be an integral part of the book.
Katharine Hepburn wrote a biography about the making of The African Queen. The book was titled: The Making of the African Queen: Or How I Went to Africa With Bogart, Bacall and Huston and Almost Lost My Mind
The movie came out in 1951. The book came out in 1987. I'm guessing someone will find an earlier book, but it's the first one I could think of.