Children prepare for their First Eucharist in religious education classes during their 2nd grade year. Older children needing the Sacrament attend a special course to prepare (RCIC). Children must have at least one year of religious education prior to enrolling in the First Eucharist Preparation Program. 

"The Eucharist is 'the source and summit of the Christian life.'  . . . 'It is the culmination both of God's action sanctifying the world in Christ and of the worship men offer to Christ and through him to the Father in the Holy Spirit.' "   Catechism of the Catholic Church #1324-1325
Diocesan Norms for Eucharist
Diocesan Catechetical Guidelines (Catechesis) for Eucharist (First Holy Communion)