CCC 1230
Christian Mystery›SECTION TWO THE SEVEN SACRAMENTS OF THE CHURCH›CHAPTER ONE THE SACRAMENTS OF CHRISTIAN INITIATION›III. How is the Sacrament of Baptism Celebrated?
This initiation has varied greatly through the centuries according to circumstances. In the first centuries of the Church, Christian initiation saw considerable development. A long period of catechumenate included a series of preparatory rites, which were liturgical landmarks along the path of catechumenal preparation and culminated in the celebration of the sacraments of Christian initiation.