No. 1318 and 1319, page 333 of the Catechism of the Catholic Church: The Celebration of the Christian Mystery; Libreria Editrice Vaticana: Urbi Et Orbi Communications:
In the East this sacrament is administered immediately after Baptism and is followed by participation in the Eucharist; this tradition highlights the unity of the three sacraments of Christian initiation. In the Latin Church this sacrament is administered when the age of reason has been reached, and its celebration is ordinarily reserved to the bishop, thus signifying that this sacrament strengthens the ecclesial bond.
A candidate for Confirmation who has attained the age of reason must profess the faith, be in the state of grace, have the intention of receiving the sacrament, and be prepared to assume the role of disciple and witness to Christ, both in the ecclesial community and in temporal affairs.
From the Baltimore Catechism No. 3; Benziger Brothers, Inc. and Tan Books and Publishers, Inc. No. 676, pages 139 and 140; Nos. 691, 692 and 693, pages 142 and 143.
Q. Why do we say the bishop is the "ordinary minister" of Confirmation?
A. We say the bishop is the ordinary minister of Confirmation because in some foreign missions [and remote parishes], where bishops have not yet been appointed, the Holy Father permits one of the priests to administer Confirmation with the Holy Oil blessed by the bishop.
Q. To receive Confirmation is it necessary to be in the state of grace?
A. To receive Confirmation worthily it is necessary to be in the state of grace.
Q. What special preparation should be made to receive Confirmation?
A. Persons of an age to learn should know the chief mysteries of the faith and the duties of a Christian, and be instructed in the nature and effects of this Sacrament.
Q. Why should we know the chief mysteries of faith and the duties of a Christian before receiving Confirmation?
A. We should know the chief mysteries of faith and the duties of a Christian before receiving Confirmation because as one cannot be a good soldier without knowing the rules of the army to which he belongs and understanding the commands of his leader, so one cannot be a good Christian without knowing the laws of the Church and understanding the commands of Christ.