There is no reliable one-size-fits-all publishing timeline. A clean manuscript requiring light editing can move faster than a book needing developmental work, illustrations, complex layout or multiple proof rounds. Build the schedule from the actual production stages rather than choosing a launch date first.
Editorial stage
Developmental editing can require substantial author revisions, while copyediting and proofreading are later, more focused stages.
Design and production
Cover design, interior formatting, proof corrections and print proofing need approval time as well as production time.
Launch preparation
Metadata, retailer setup, advance marketing and promotional assets should be planned before the release date where possible.