Play piano music often. You can play live piano music yourself, or you can expose your toddler to recordings of piano music. Concerts and other live performances also are excellent ways to introduce the piano to your toddler.
Play copying games with the piano. Strike a note and have your toddler play the same note. Play simple rhythms on a single piano key and have your toddler echo your rhythms.
Teach toddlers to look for patterns on the piano. For instance, the black keys appear in sets of two or three. Have your toddler touch keys that you call out, such as "two black keys."
Use color or number stickers to label piano keys. Say the colors or numbers as you play various keys and have your toddler imitate you.
Remain patient and keep it fun. Introducing toddlers to the piano should be a process of gradual development. If your child has fun and is interested in the instrument, then you are building a solid foundation for future learning.