The other morning while I'm getting dressed, he walks into the room and says, "Can we pray together about First Communion." So we knelt down at the prie dieu in our bedroom and prayed that he would be able to receive the Holy Eucharist one day.
The amazing thing is that I believe that my three-year-old understands the Eucharist and wants to receive Christ sacramentally. It makes me desire the Eastern custom of paedocommunion (i.e. children receiving the Holy Eucharist).
By the way, Saint Augustine attests to the ancient practice of paedocommunion in the Latin West. I wrote a post about it here: Saint Augustine on Paedocommunion.