My wife and I led a group using the first book of the series last summer. To do it justice, you need at least 12 weeks–and that’s if you compress the last sections of miscellaneous questions into one or two classes, or fold them into other related chapters.
You didn’t mention it, but we also used the study guide that is available. It has lots of good questions, plus Scripture and patristics references.
The format we used was the following: Each session was two hours. The previous week to each chapter, I would pass out the questions that we would be using the following week, and some supplementary materials as appropriate.
The first week I gave a general overview of apologetics: it’s goals, strengths, and limitations. I explained to them the format of the class, and what resources they’d need; a Bible, a Catechism, and the study guide.
Each week, after an opening prayer, we’d start with an hour of introduction to the subject and offer some information that wasn’t in the book, but we felt needed to be explained. We’d then recommend some books or other resources for further info. After a break, we’d go over the questions and, time permitting, have a little Q & A. We’d close in prayer and pass out next week’s questions.
Everyone seemed to get a lot out of it. Some people were very enthusiastic and said they’d take the whole course again if we offered it. We even had one person decide to enter the Church and enter RCIA because of what he learned in the class. Overall it was very rewarding, and I believe God used it to bless, not only those who attended, but those to whom they would go on to share their faith with.