The Scrutinies are celebrated with catechumens on the 3rd, 4th and 5th Sundays of Lent. Here are links to some common questions and good articles that may help you as you plan.
Do we use Cycle A readings for all Masses even those where we don’t celebrate a scrutiny? Answer: https://paulturner.org/scrutinies-and-homilies/
Here is a link to an in-depth article written by Fr. Turner about the Scrutinies https://paulturner.org/wp-content/uploads/2012/08/scrutinies1.htm
Finally, here is a link to a concise article about the Scrutinies from Team RCIA http://teamrcia.com/2018/02/how-to-celebrate-the-scrutinies-without-scaring-the-catechumens/