I love the montessori way of teaching. DS went to care there when he was around 2, and we weren't impressed, BUT, they didn't really have the facilities for caring for a child that wasn't yet toilet trained and things like that - they're not a child care facility so to speak.

So I wouldn't hesitate to put him in after he was around 3 or 4 years of age. I know my friends paid $50 a week for their little boy for him to go when he was around 4? And we just paid normal child care rates for DS when he was there.