By that stage they should be learning and re-learning most of the stuff on their own. I think the CFI tends to be more of a resource for questions and an evaluator of their lessons and flying/flight instruction than a hand-holder. There is too much information for you to cover it all in a classroom.
My inspector told me in my CFI ride "my instructor said" doesn't cut it anymore.
Advise them to read the PHAK, Aviation Instructor's Handbook, and AFH and knock out the writtens before they start. It would also have helped me to read the POH for the plane beforehand as well. They should know the number of and understand each FAR in 61, and be able to apply it, (commercial helicopter pilot wants to get commercial airplane; what's required, etc.). They should be able to reference the appropriate rules in part 91. They should be able to show that the plane is airworthy. I and some of my students were ramp checked as part of the oral. If they don't take your advice then that's on them. Making notecards worked well for me.
They should know definition, theories, characteristics, principles, laws, levels of learning, how people forget, how to transfer learning, domains of learning, etc from memory. Most examiners are not a fan of applicants referencing like crazy for those sections. There are good acronyms for some of those.
If you can get them to make their own lesson plans, then great. I used those available online (backseat pilot, etc) and made sure I understood and could teach them for my own ride. It took a few reams of paper, but better to know every task and detail is covered in case you're missing your own lesson plan. There is nothing worse than hearing from an applicant that they got in the oral and were missing a lesson plan on one of the FOI tasks...
The UND aerocast videos are excellent for understanding maneuvers.
Have them teach, teach, and teach some more. Let them know at the end they can reference any FAA publication in the ride, but if they know at the beginning they won't be as motivated to study in my experience.