@Cregt,
I hope he wasn't a teenager, because they typically don't make the best choices. Of course I guess we are talking about Jesus. So wouldn't Jesus make the correct choices pretty much regardless of age?
Anyway, I don't know the age, but to be a SACRIFICE wouldn't it make sense he would not be "old enough to make his own choices"? I mean, how is it a sacrifice if in effect he is able to make his own choices? Woudn't you normally expect a parent to let their child go when they are capable? I place the caveat that we are talking biblically here, not based on current society where children are not weaned from the parent until a few years post college.