For writing, the place to start is with oral narrations. That method will give her practice in all of the mental work involved in composition. In fact, Charlotte called it “oral composition.”
I’m not sure what you mean by “grammar.” If you mean using English words correctly, capitalization, punctuation, and other usage components like that, you could easily start at the beginning of Book 1. That book also walks you through the importance of oral narration, then helps you make the transition to written about halfway through.
If, however, you mean parts of speech, those are covered in Book 2. The written narration rubrics and tips on Book 2 assume the student is fluent in oral narrations and has had some written narration practice.
I believe the first rubric is available in the sample of each teacher book. You might want to download those samples and take a look at the rubric 2.1 in Book 2. If it looks like too many concepts that would be new to your daughter, start with Book 1.