You are required to have models for most lessons for the most realistic learning experience. You can see exactly when models are required on the Lesson Guide for each Module, found here.
It is your responsibility to ensure that the model has reasonable expectations about the service she will receive. Lessons are planned to give you plenty of time to practice but some application methods will be more difficult than others and in some cases you may not complete the full set.
A sheet giving tips on finding models can also be found on this page.
You are welcome to share models with a fellow student if they are studying the same topic and live in the same area as you. You do one hand each, taking a lot of pressure off your timing. Use the Facebook Group to communicate with other students and coordinate sharing.