At what age should a child be introduced to religion?

[Pat Mustard]

"Daddy, what's that building you go to every Sunday morning?"
"Sorry, Timmy, I can't answer that question until you're 12 years old."

"Mommy, what's that pendant you wear around your neck?" 
"This is not for you to know until you reach the age of reason. Ask again then."

When kids start asking questions, it's the time to answer them in a way appropriate to their age and level of understanding.

I remember having my first communion and really not having a damn clue what was going on...I was six, and was parroting what I had been taught.

For confirmation, I didn't know much more other than...this is what we do.

I think for the RCC those ages are a little higher now but I don't know how much the kids really understand what they are doing other than going through the paces.

They're only higher here in Ireland because kids are starting primary school later. Universal access to pre-school means that most kids are now not starting into school until five or, more likely, six.