During the live classes on my site, we simply read. Currently, we are in chapter 18 of the book and are just slowly moving forward. I don’t know how long it is going to take. A while, I am sure. Another school year, at least. Over two hundred pages to go.
Since we are moving so slowly, I am guessing it would be pretty easy to catch up. You can actually use the little gear symbol on the recorded videos to speed the videos up. This would speed up learning and would speed the catch-up process. So, that would help.
Or, there is another option. You could determine to watch two videos a day. A live video, and a recorded video. You could jump into the deep end and join the live class in chapter 18 (or, wherever we happen to be) and simultaneously watch the older classes. Jumping into the deep end in languages is not always a bad idea. Sometimes it speeds up the process.
As for planning, I skipped the pronunciation section of the book, because now there are plenty of digital places to learn pronunciation. They didn’t exist back when the book was written.
As for chapters, I would estimate it took us about a week a chapter. Sometimes more, sometimes less. Of course, you don’t have to watch all of the videos (you could skip the exercises if you wanted) and you can speed the videos up. This will help you guys as you catch up.
Finally, don’t stress about catching up. Feel free to just join the live classes. There is so much review in languages, we will probably cover most of what we already have covered again and again.