She went January of Y6. We started looking in Y4 at residential schools; then we had to arrange for her to do an assessment stay and wait for their in depth report of her difficulties and what she needed; and then hopefully the offer of a place.
From her assessment visit, she loved the school and called it:
"My lovely little school....."
She was being integrated into mainstream by then every afternoon and she could not cope. She did not understand the teacher, could not read the material and did not understand what she was supposed to be doing. She was in tears until 9 pm 3 - 4 nights a week.
School reports, including by the onsite speech and language therapist said she would have profound difficulties in mainstream. She had already been under CAMHS for 6 years for emotional problems, due to great self awareness, feeling a failure in school (compared to her bright siblings and the mainstream children). There were no suitable secondary schools for her in our LA. We looked at the secondary mainstream or special schools (not suitable for her); and DS was already at our local secondary, so we knew what it was like (a high achieving school and not brilliant at SEN).
Realistically, we had no choice, because if we had sent her to a mainstream secondary, she would have had a breakdown. CAMHS agreed and recommended that she go to a residential specialist school.
Eventually, the LA agreed to send her in the December of Y6, starting in January. It was weekly boarding - she came home by taxi on a Friday night, and we took her back on a Sunday night. She was in tears when we left her for the first 6 months; but she was very happy to be in a school, with no mainstream integration; where she could cope, among people who understood her. They had signing in the classroom, which helped her. She was very popular in the school with the other children and staff.
The normal ratio of boys to girls in schools like that is 10:1, but iirc in Y7 upwards she was in a class of 6 girls and 4 boys. Some children leave, because their parents move or occasionally, its decided the school can't meet their needs, because a new condition has emerged.
It was the happiest time of her life; but I have never met a mother yet, who found it easy to send their child to a residential specialist school; but for all of them their child had been bullied in mainstream and was unable to cope. They had no other choice. I did equally meet parents who could not bite the bullet, and send their child to a residential school; and the mainstream placement fell apart in Y7 and they had a year or more out of school, while the parents looked for another school.