Many people have found
Music for Little Mozarts (
http://www.musicforlittlemozarts.com/) to be good for preschool children, but it is advertised for ages 4-6. It uses ABCs instead of solfege. There is also
My First Piano Adventures (
http://pianoadventures.com/myfirst/) for ages 5 and 6.
However, if you are having a hard time instituting piano into your life, perhaps you want to look into group piano classes for preschool children. On the forums of pianoworld.com, there are the following quotes:
"Music for Young Children ("MYC"
www.myc.com) is one of a very small handful of group piano programs available. Harmony Road (
www.harmonyroadmusic.com) and Yamaha are others. My understanding is that the Yamaha program was the 'original' group piano method (it's been around for 30+ years) and that the others are in a sense offshoots of it. They are similar in that they share the same philosophy of 'ear before eye'. Yamaha and Harmony Road use solfege as their musical language, MYC uses traditional letter names (and a little solfege, a la moveable 'do'). MYC is very popular in Canada.
"What I like about these three programs (in comparison to programs like Music Together, Kindermusik, Musikgarten, and others for the 2-4 year old range) is that they are piano-based even from an early age. Each child and parent sits at a keyboard or digital piano. Keyboard activities include 'bouncing on the black keys' then white keys, making 'birdie sounds' and 'elephant sounds', etc.... By the time the kids are 4 1/2 and ready for the group piano program they already have a nice introduction to the piano and can even identify some of the notes on the piano and the staff. "