Another retired teacher here. I know schools are often very poor at understanding kids who learn a little differently than the majority. My DW can work apparent miracles with kids like that with one on one time in a setting away from the school because she takes the time to understand each one. And classrooms full of early teens can be very troublesome. I would say your plan is excellent and well timed.
In my experience home schooled kids coming into classrooms in grades ten and eleven are often very shy and have difficulty dealing with some teachers and other students. You must try to work in considerable interaction with other kids.
Don't go too long. In the last three grades of school there is considerable specialization and teaching just doesn't work unless the teacher has considerable knowledge and skill in the subject area. You will tend to channel your daughter into the areas you are skilled in.
Public schools do an enormous service to our society by bring all the young people in a community together. I have watched in awe as over the course of a semester a group of 17 year old girls straightened out a boy from a family where the mother was abused by the father. And many other socialization and belief problems are sorted out. I hope you won't deprive the others in your community by keeping your daughters separate for too long.