Why people ask this
Moving too early creates rework. Waiting for complete certainty creates a different kind of paralysis. The useful question is whether the work required for this decision is complete.
My answer
Each phase of Past the Obvious™ has an exit.
Think ends when your brain stops naturally surfacing relevant knowledge. Define ends when people can describe the same destination in their own words. Diagnose ends when you cannot trace the problem further back. Design ends when every requirement associated with the issue has a complete resolution.
At that point, execution should not be where the hard thinking happens. It should be where the thinking gets built. Reality still gets a chance to disagree through validation, but future possibilities do not need to interrupt the current version.
Common mistake
Confusing more ideas with better preparation.
Additional thinking is useful only while it improves the original objective or resolves a real requirement.
Try this
Ask: Is the destination shared? Is the cause understood? Is every current requirement resolved? If yes, you have probably earned the right to move.