Tell them a few weeks in advance in simple words, and repeat it often. Toddlers do not understand time well yet, so a picture book about moving or a countdown calendar helps.
Let your toddler pack their own box with toys and a cuddly toy, and take it with you yourself. Set up the children's room quickly, ideally the same as in the old house. Keep the regular moments, such as meals and bedtime, the same as much as possible.
