After 10 years of watching people pursue advanced Speaking scores on TOEFL iBT, I can say that people tend to massively underestimate how much time they actually need to be investing.
You should expect to need 18 to 24 hours to study the topics in the workbook, and watch the corresponding videos inside this website. So, depending on your schedule, you may need 18 to 30 days to achieve that.
What you do next is actually the most important. After your initial review of the material, you should expect to spend another 80 to 100 hours practicing and developing automatic habits over the next 6 weeks.
If you’re unsure how to do that, you can upgrade to my program, Understand How to Get S26. In that, in many video classes, we go through the Advanced Speaking Guide and create high-scoring responses together.