For either catechumens, candidates, or both, this sending rite is optional. RCIA 530 notes this celebration is provided “for parishes,” likely as much if not more than for the catechumens and candidates themselves.
RCIA 531 reminds us that while “admission to election belongs to the bishop … (i)t is within the parish community, however, that the preliminary judgment is made concerning the catechumens’ state of formation and progress.” Why have a rite of sending? It “offers the local community the opportunity to express its approval” and “assure (the catechumens) of the parish’s care and support.”
RCIA 532 permits the inclusion of baptized candidates, if they are to be sent to the bishop. This rite takes place in the parish church (533) prior to the Rite of Election. It may take place after the homily either at Mass or at a word service (534). And as we were reminded in RCIA 506, “care must be taken to maintain the distinction between the catechumens and the baptized candidates.”