Strategy, discovery, metrics, growth, pricing, design, delivery and leadership. Each entry says when it is the right one to pick up.
Pichler's early and still useful book on the Product Owner role. Covers what the role actually involves, envisioning the product, working with the product backlog, planning releases, and collaborating in sprint meetings.
Watts applies the same good to great structure to product ownership, using the acronym DRIVEN for the characteristics of a great Product Owner. Covers decisiveness, ruthlessness about scope, informed decision making, value focus, empowerment and negotiation skill.