RCIA tells us the primary texts of mystagogy are not found here in the rite, but in the Sundays of the Easter Lectionary.
247. Since the distinctive spirit and power of the period of postbaptismal catechesis or mystagogy derive from the new, personal experience of the sacraments and of the community, its main setting is the so-called Masses for neophytes, that is, the Sunday Masses of the Easter season. Besides being the occasions for the newly baptized to gether with the community and share in the msyteries, these celebrations include particularly suitable readings from the Lectionary, especially the readings for Year A. Even when Christian initiation has been celebrated outside the usual times, the texts for these Sunday Masses of the Easter season may be used.
How important is adult initiation for both the community and for the newcomers to the faith? Important enough that a community should consider reordering the Sunday readings to accommodate it. Ordinarily, Easter Vigil initiation will be followed in the weeks ahead by the Easter readings of the appropriate cycle. But year A is always an option. If adult initiation took place in ordinary time, I’d say the year A readings stand above the other choices. The Jesuit Felix Just has summaries of the Lectionary on his web site, including this one for the readings of Easter, cycle A:
|Lect. number||Sunday or Feast||First Reading||Responsorial Psalm||Second Reading||
|42||Acts 10:34a, 37-43||Ps 118:1-2, 16-17, 22-23||
or 1 Cor 5:6b-8
|1 Cor 5:7b-8a||
or Luke 24:13-35
(for afternoon Masses)
|43||2nd Sunday of Easter – A||Acts 2:42-47||Ps 118:2-4, 13-15, 22-24||1 Pet 1:3-9||John 20:29||John 20:19-31|
|46||3rd Sunday of Easter – A||Acts 2:14, 22-33 (diff)||Ps 16:1-2a+5, 7-8, 9-10, 11||1 Pet 1:17-21||cf. Luke 24:32||Luke 24:13-35|
|49||4th Sunday of Easter – A||Acts 2:14a, 36-41||Ps 23:1-3a, 3b-4, 5, 6||1 Pet 2:20b-25||John 10:14||John 10:1-10|
|52||5th Sunday of Easter – A||Acts 6:1-7||Ps 33:1-2, 4-5, 18-19||1 Pet 2:4-9||John 14:6||John 14:1-12|
|55||6th Sunday of Easter – A||Acts 8:5-8, 14-17||Ps 66:1-3, 4-5, 6-7, 16+20||1 Pet 3:15-18||John 14:23||John 14:15-21|
|58||The Ascension of the Lord – A||Acts 1:1-11||Ps 47:2-3, 6-7, 8-9||Eph 1:17-23||Matt 28:19a+20b||Matt 28:16-20|
|59||7th Sunday of Easter – A (note)||Acts 1:12-14||Ps 27:1, 4, 7-8||1 Pet 4:13-16||cf. John 14:18||John 17:1-11a|
The first readings are all narratives of the early Church, pre-Pauline. The Psalms are all frequent to the Sunday Lectionary, except for Ascension. The Gospel passages are all classic to the season: three post-Resurrection narratives, the Good Shepherd, and three from Jesus’ Farewell Discourse in John, plus the Great Commission. What better to form a post-initiation community than the themes of the sacraments, trust in God, unity, and a sending to evangelize the entire world?