Product Managers should involve Product Designers and Engineers as early as possible in the product development process (problem discovery, solution shaping, e.g.)
Involve Product Designers earlier so that they can challenge you to build a more friendly and user-centric solution.
Involve Engineers earlier so that they can challenge you to build a more concrete solution, a more scalable system, etc.
This also helps generate more ideas, create empathy, and increase team engagement.
P.s: However, sometimes it would be too early if you don’t have any use-case or have no idea what problems you are trying to solve.