Since there seems to be a lot of variation in the developmental pace of different individuals, it seems that a program such as this would need multiple tests, and a way to detect students who were put in the wrong track. Even then, you can expect significant opposition to such a program in any established society.

Unfortunately, this kind of caste system already exists as a de facto result of socioeconomic background, and I think it would be better to acknowledge and counteract the effects of background, than to make an explicit division based on early age testing.