I’m very happy to learn that Alfred Publishing (publisher of the Suzuki Method repertoire materials outside of Japan) has Suzuki piano volumes available on iTunes!

https://suzukiassociation.org/news/suzuki-piano-school-volumes-1-7-digital-audio/

Some ideas of mixing up a typical book-by-book listening routine:

1. Combine a higher level books with your budding pianist’s current book. Mix and match for a variety of songs.

Current book / Future books
Book 1 / Book 3, Book 4
Book 2 / Book 4, Book 5
Book 3 / Book 5, Book 6
etc.

2. With digital format you can mix and match the albums easily to create a variety of playlists. Some ideas:

Playlists by keys of the songs: All C major pieces, all G major pieces, etc.
Playlist of all the minor keys.
Playlist of all the pieces with left hand melody or feature left hand melody.
Playlist with extensive legato playing.
Playlist with lots of staccato playing.
A J.S. Bach playlist.

It’s never too early to get those ear worms in! Happy listening.