I will use it with my coming first grader this year as I did with her older siblings. I do as missceegee suggests. She will do oral narrations of one chapter a week. Right now I do not keep a written copy of it.
Once they are in second grade they begin a history notebook. I will continue CHOW and oral narration in second grade once per week, but once a week they also look through a 2 page spread of the Usbourne World History book. They then do a notebook page with a map and a drawing. I help them with a short summary and in 3rd grade they continue without much help from me. It takes them two or three years to complete and while not exactly pure CM, my older children really liked that activity and learned a lot. They pull their old history notebooks out once in a while to reflect on their younger work. It has been a good thing at our house.
We also start around 2nd or 3rd grade, depending on the child, working our way through Our Island Story and This Country of Ours. Once per week, oral narrations until fourth grade where they begin simple short written narration. This doesn’t take as long as you think and the scope of history they get from these living books is great.
However, I do think one could only do CHOW and would be fine.