When is the Optimal Time to Start Doing Performance Practice?

We all know how valuable practice performances and mock auditions can be - but I think it's probably human nature to wait until everything is "ready" before we start recording and playing for others. Of course, how far in advance of an audition or performance should we be playing for others? Is it important that we wait until things are pretty close to being performance-ready? Or should we be aiming to play for others much sooner than we might otherwise assume? When is the Optimal Time to St...