I have seen this all too often at the congregation I used to go to. Children getting baptized around age 12 was the normal, though some held out (and were hounded) until 14 or 15. The youngest I have seen at the hall I used to go to was 10.
However, I have heard all too many experiences of younger children getting baptized. Just about every Grand Boasting Session has at least one experience where someone 8 or younger gets baptized, and those yearbooks like to gloat about people as young as 6 getting baptized. Now, if there was no penalty for leaving if it was not for you, all well and good. But, given the severe penalties for discontinuing one's membership and the impossibility of merely suspending it, this should never be allowed.