Do overall scores on tests, such as the bayley scales, accurately predict future grades in school?

No, it's not possible. Because brain development in early adolescence enables formal operations, improved memory and information-processing skills, and better performance on IQ tests. IQ scores become more stable and predict IQ in middle age. In childhood and adolescence, IQ scores are a good predictor of school achievement (Better predictor of high school grades than of college grades). So it is not possible.