I will not “pasken” for you or anyone else. I believe that chinuch starts from before the time the baby is born (don’t we even say that the malach is teaching Torah to the fetus…?). So from the prenatal vitamins that I took through today, my kids were taught what was and was not permissible. I never allowed them to have milk right after meat. When they were infants and breastfed,it was not a problem because breast milk is pareve. But once they were old enough to have milk products, they always had a separation, even if was only an hour for the very young, and then the regular amount of time when they were about three. I taught them that they could have juice after their chicken, or water (we didn’t have rice dream or the like then, but ewwww). If they wanted a bottle or cup of milk, tehy had to wait. I therefore tried to always give them the milchigs first, so it would not be a problem.
It is for the same reason, that I put yarmulkes on my boys from VERY early ages, before they could really even talk. Unlike my friends who could not keep a yarmulke on their sons’ heads, my boys were so used to it being on them, they never threw it off. My son and daughter-in-law chose not to follow my example, and they are having a lot of trouble with getting their two year old to not want his milk after fleishigs, OR to let them put a yarmulke on him. He is soon going to have his upsherin, and will not let them put on the yarmulke, even one decorated with his favorite character from Sesame Street. We bought him one with his name on it. He played with it and then put it down.
Kids are NEVER too young to bee xposed to Torah in a way to which they can relate.