Yes I was, as a baby (not sure what age).
Let them make the decision when they want to. In the cases I've seen where people wish to have their own Baptismal records removed from the church's records, they're denied the right. The Catholic diocese refuses their request. You cannot be "unbaptised" from the Catholic faith and I do not agree that it is a parent's right to choose their child's membership in any religion.
Nobody would agree that it's okay for a parent to sign their child's name onto a 25 year mortgage. You wouldn't support the idea that it's okay for a parent to enlist their six your old in the KKK. I don't see why choosing a religion for an incapable mind is any more correct. I find the whole notion pretty bizarre. After all, if you pull out of the mortgage, the worst that will happen is that you will be declared bankrupt. Even if you could 'pull' out of the religion, the price is eternal damnation in most cases. Hardly a contract that a child or baby should be entered into without their consent.
If you truly believe your religion, then I'm sure you would agree that your relationship with, in this case, the Catholic God is between you and him/her/it. It is a relationship that should be freely entered into, not something chosen for you before your mind is even capable of comprehending the notion that there are hundreds of religions and thousands of gods.
It shouldn't be done at a young age. The only reason the Catholic church (and many other denominations) promote doing it at a young age is so they can retain steady membership statistics (which is also the reason they deny anyone the right to have their Baptismal records officially destroyed). They know that if everyone was given the opportunity to choose if they wanted to enter the religion when they reach a respectable age of consent that a lot of people wouldn't enter. And that would destroy the very foundation of the organization. Their membership statistics would plummet; they would no longer be able to claim 33% of the world's population being Christian.
The issue goes deeper than this, but the post would be pretty long so I'll let it be
Short answer: Let them make their own decision when the time comes. This is not some random, unimportant factor in a person's life. In regards to the Catholic religion, it's an eternal decision that cannot be revoked. It should be decided by the individual.