Anytime ! All the time ! Use it before you enter a meeting and when leaving. You will likely find you use it the most when you are by yourself, alone with your thoughts. Anytime less than peaceful thought comes up , say Ho'oponopono a few times and the thought is gone. The thought might come back, depending on the situation that created that memory and if it does, just continue Ho'oponopono until it no longer returns.
Have you ever been in bed just about to fall asleep and a thought comes in reminding you of a negative experience and the next thing you know you cant get to sleep because you keep going around and around replaying the scenario. This is a great time to practice Ho'oponopono , just start repeating it until you stop thinking about it and fall you will likely fall asleep asleep. Or you are driving home from work, day dreaming as usual and suddenly out of nowhere you remember the time when you got angry at your Dad when you were 12 years old . What? Where did that come from? It came from your unconscious mind, the place where all your memories and thoughts come from. It is highly likely this isnt the first time this same thought has come up, even though it was long ago. That is a good indicator that whatever the event was that caused this thought has a big impact on you, and continues to do so
When these types of thoughts pop up, just do Ho'oponopono around them and it wont be long before you realize those kinds of thoughts are no longer coming into your consciousness. You will not even remember what you were doing Ho'oponopono about . It cleans you unconscious mind of all the negative energy you have been accumulating over the years. Where do these thought come from? They come from ourselves, from our our unconscious mind and our past experiences.