Michael Lopp has a great post about “managing up”, including how problematic that term is:

To me, “Managing Up” has that “your boss’s job is more important than yours” feel, which pisses me off. Your boss’s job isn’t more important than yours; it’s different.

He goes on to share some great advice for what to share with your manager, and when. For instance, when to share something immediately:

Unexpected developments. A situation appears in front of you, a non-threatening one but unexpected. Strange. Something is up, but you can’t discern the backstory story or the intent. It is unfamiliar. Tell your manager. Now. Just a brief note. A heads up. It’s probably nothing—it usually is—but there is a chance your manager’s context plus your suspicions equals additional clarity.