My guess is that the moment you read this question, someone came to mind. Maybe they are someone you simply lost track of. Maybe they are someone you intentionally or unintentionally hurt through your own pain, anger, or simple thoughtlessness.
Don't wait for the "right" time because there is no right time.
Make peace with this person today. Send the person a note that says, "I'm sorry." You'd be surprised how powerful this can be.
Or, give yourself the gift of peace by letting it go. The best way to let it go is to practice the Forgiveness Meditation.
Don't wait another moment. Do it now.