Traditional publishing usually starts with querying agents, a process that can take months on its own, followed by a submission process to publishers that can take longer still, with no guarantee of a yes at the end of it. If accepted, the gap between signing and the book actually reaching shelves is often 12 to 24 months, sometimes longer, because you're one title in a much larger catalog with its own production calendar. Partnership publishing runs on a calendar built around your book specifically: most authors move from a positioned idea to a published, launched book in roughly 6 to 12 months.