The best pacing of Essentials will vary between students. However, there are two typical pacing structures.
The first is doing one part of a unit per day. Each Unit of Essentials is broken into five parts; if you do one part per day, you can plan to be done with Units 1-7 in about 7 weeks. Each part typically takes about 45-60 minutes.
However, a more common approach is to break each part over two days. Approaching each part over two days will give you about 30-40 minute lessons each day and allow you to complete Units 1-7 over the course of about 14 weeks. Begin each day with a quick review or game, then resume where you left off.
If you are starting with the Pre-Lessons before Unit 1, you should plan on an extra week or two to get through all of the Pre-Lessons. The concepts taught in the Pre-Lessons are needed for student success with the units, so students who are weak in these skills need to complete these lessons before beginning Unit 1.
In a short-term intensive intervention with an older struggling reader, some people will also choose to move more quickly, spending several hours per day on Essentials in order to complete more than one unit per week.
The most important aspect of pacing Essentials is to do what is best for you and your student(s). You want students to be mastering concepts as you progress through the units so they can continue to build on this knowledge.