Many people advise that you should give difficult feedback immediately, preferably within 24 hours of an incident. But next time you have to provide constructive criticism, consider sleeping on it first. Your input will be far more effective, and better received, if you aren't feeling agitated. Put some distance between the offending action and the feedback to gain perspective. You may need to calm down over several days. This will give you time to prepare, consider the other's point of view, and deliver the message in a calm and helpful way.