Obviously I would love it if Julia and Ella wanted to and could do anything like that as early as possible. But then I think about whether they would do something because they genuinely want to, or because I want them to do it. Mostly I think a good strategy is to make a particular activity available to the child and to let them take an interest in it on his/her own and if it's something you can do, to let them see you doing it. There's also a concern about being exposed to something too much, too early and getting burnt out on it, even though it's something the child actually really enjoys.
Another issue I've heard mentioned, which I mostly dismiss but am curious to see what others think, is that a child who can do something at an earlier age than most other children will be viewed as a misfit by other children (and even other adults), and that even if the child is not viewed that way by others, may feel that way about him/herself.
Anyway, this is kind of a rambling post, but it's something that interests me so if anyone else has any thoughts, that would be cool!
P.S. This topic leads to another topic that I've been thinking about, which is, "Where is the fine line between being proud of your children's achievements and wanting to share about it and being one of those annoying people who would appear to have the uber-child and never stops bragging about it?" But that's for another post, I think.