A toddler spins in the living room. A preschooler taps along to a song in the car. A baby bounces in someone’s lap when the music starts. Long before children can name a beat, they often feel it. That natural response to music is one reason many families begin thinking about dance classes early. The question is not whether a child can perform steps perfectly. The better question is whether a class would feel joyful, safe, and age-appropriate for the child right now. Some children are ready to...