You need to be more specific.
What age level are you teaching? How many students sit in on a class on a regular schedule? Are you teaching at a school or institute? How many sessions have you been told to attend till the term is over?
I suggest that you take a look at the Introduction of the book, and then you get a pretty good idea of how you can adjust the time you are going to have to spend teaching each unit!
Do not forget that " You do not have to complete every exercise in the Student's Book. You can omit selected exercises, such as the Writings, Readings, and Interchange activities" (According to the TEACHER'S EDITION)
I cannot help you more unless you are more specific!
English Teacher Trainer