The essay portion of the SAT is not to be feared, nor, does it need to receive an inordinate attention in the preparation process. It counts for only part of the score on the SAT Writing. The bulk of the score is in multiple choice questions. These questions cover improving sentences, improving paragraphs and identifying sentence errors.
Update your testing schedule in GuidedPath. (Watch a video on how to do this)
When you register for the ACT, register for the writing section. Set a task to study for the writing sections of your tests, with an emphasis on the multiple choice questions. Plan to finish all your tests by December at the latest. Make a group task: study for the writing section.