My only input would be waiting until end of year 2 is too late from my experience.
With my first child, I blindly followed the school, who told me she was excellent in reading, writing and mathematics and was top of the top group for her year group of 100 children.
Well all I can say is I hate to think what the rest of the 99 ability was like, because when she went to change school, I was told that she couldn't read, her writing was atrocious, she couldn't spell, and that her maths was the only thing she could do because she was naturally talented.
Yes I was aware of her level of reading and writing, but presumed that this was normal for age based on what the school had said.
She spent so many years trying to catch up, even now in Yr 8 her writing is poor, compared to her ability.
By god, I was damn sure I wouldn't make the same mistake with my subsequent children, and no way if I was unhappy with a school would I now allow them 3 years to mess up my child's education.