Beheading is easier to understand when you can see the plant, the growth point, and the cut location in person. A practice course gives growers confidence before they use the technique on valued plants.
The best time is usually when the plant is actively growing and can recover. Use clean tools, make a clear cut, let wounds dry, and keep both the cutting and base in stable conditions.
This kind of hands-on record helps beginners see that propagation is a skill, not a mystery.