If you are just getting started the most user friendly IMO is Journey of Faith from Liguori. It comes in versions for child, teen and adult, English and Spanish (which is a major concern here) with a “handout” for each lesson, and a decent guide for extending the lesson. It assumes breaking open the work, the work with the week’s Sunday readings, will be part of each session, and the guide supports that, or you can use the children’s weekly gospel resource they publish, depending on the age group.
There are (I am working from memory) about 12 lessons for Inquiry, 16 for the catechumenate, 8 for Lent which prepare for the rites of Lent and Easter, 8 for Mystagogy. It is affordable, less than $10 per participant.
I assume you mean true Children’s Catechumenate, with mostly unbaptized children. You do need to supplement after Easter to prepare them for first confession.
If you have mostly older Catholic Children who have never received first communion, JOF also works, with some adaptation. The “catch-up” catechisms from Sadlier, One Faith One Lord for about grades 8 or 9 to adult, and Our Catholic Faith for middle grades have turned out to be our best resource for bringing grades 4+ up to speed. You do need to supplement specifically for the actual sacramental preparation, but this is a good all around “what Catholics need to know”.
I suggest both of these because they are easy for a new, inexperienced catechist to use. As you gain confidence you can supplement with other resources but your children will be well served if you stick with these programs.
JOF supports about a 45 minute lesson, and assumes you will also be spending at least 15-20 minutes on the Sunday readings, in the same class or at another meeting during the week. Add work on basics like the prayers, the Mass, saints, rosary etc and you can fill a weekly 90 minute lesson.