Does the Guide get in the way if I already know BookyAI?

No. If you already have books or a connected AI engine, the only thing you see in version 1.9.17 is a new "Guide" button at the bottom left, marked "NEW" until you open it once. No welcome screen, no pop-ups, and nothing opens by itself. In Settings, the large "step by step" button of an engine turns into one small line once that engine is connected. The tours are there when you want to learn a page you have not used yet, such as the Index, the Codex or Cover Studio.