i had the same question for my 4 yr old son.....i went ahead and started with the pre-k, and he did the whole book in just a few days with no problem at all. i think i sort of wanted to preview it so i'll know in the future where to start with his younger brothers. anyway, i def. could have started him with the K program. he's doing the K now with no problem (he already knew how to write his letters before we started, this this is giving him good practice at staying within a specific area, etc.) i say dont waste your money, start with K, unless he needs practice tracing shapes and things like that.