When is signed by closing both your hands in fists and sticking only your index fingers out. Your non-dominant index finger stands vertically and doesn't move, while your dominant index finger twists in a small circle above the non-dominant index, until it finally touches the tip of the index finger to rest. It is like you are zeroing in on a more precise date or time, until you finally reach it.
Teach your toddler the when sign in conjunction with the anticipation of a scheduled event, a holiday, or any other special day or activity.
Use the when flash card when you begin to explore compound phrases with your toddler. This sign is best for toddlers and can be used to enhance their sense of time and teach them to narrate events.