Summarize this article in one sentence.
Don't wait until you have mastered the technique in practice settings to apply it to your instrument. The only way to get better at it is to do it, so add the rest of your instrument as soon as you can make a sound using just your mouthpiece. Do not start with complicated music, or with songs at all. Instead, start by holding single notes, then move on to easy, repetitive exercises. This will let you continue to perfect your technique. Some registers will make this easier than others. You may find it easier to start with exercises that hit the higher part of your instrument's range. Circular breathing can be mentally and physically tiring at first, so you might find it hard to keep it up for long. However, this doesn't mean that you should only practice once in a while. Instead, try three daily sessions of a few minutes each while you are learning the technique.
Try it as soon as possible. Work your way up. Practice a little bit each day.