You think you've done all you can, but you keep asking the question, "Is it ready yet?"
How much time have you actually put into your piece? How much more time do you need to put into your piece? (You can see why repertoire selection is so important: you've devoted so much time to this process that you probably don't want to play anything but A-list music.)
Some pianists I know will boldly claim that it takes them a week or two to memorize a piece. Pay no attention to these music jocks! You know by now that this isn't about speed. It's about devotion. The fact is that your piece is never really ready. You can always do more with it, not just interpretively, but also in the manner in which you hold it in your heart.
What you're really trying to find out is if there is an empirical way to determine that a memorized piece is "ready to go." Some musicians avoid the question almost entirely by putting a piece to sleep for a certain length of time before bringing it out again and preparing it for performance. I feel that this is a valuable approach--although it only changes the question from "When is it ready to perform?" to "When is it ready to be put to sleep?"
As we are about to leave the middle stages of memory, there's one last step I take before feeling ready for a recital: practice performances. There are different ways to do this, so I'll expand on this in my next post.