At what age do you start training?

At what age do you start training?
The method is designed for early learning, starting from the age of three, but based on my experience, I will say that you need to start when the child shows interest in reading, letters... My youngest student was 2 years and 8 months, the oldest was 7 years old . The technique is unique and suitable for all preschoolers. Classes are held in a playful way, we practically do not sit still: we play ball, jump, and do a lot of active tasks.