Aimee, if your 6th grader is a reluctant writer, I would hesitate to step up the pace. Doing dictation every day would be challenging for many students and could be particularly frustrating with a reluctant writer.
If you are using the rubrics in the back of the teacher book to help you evaluate his written narrations, the points on those rubrics will step-by-step cover many of the capitalization and punctuation points covered in Book 1. You could just use those guidelines as an unofficial review and make sure he understands each new point as it is added to the rubric.
If you do, however, decide to cover the lessons in both books at a faster pace, I would encourage you to limit the number of exercises he has to prepare for dictation each week. Two per week is plenty.