Every child is different and every situation is different. I've had children start who were happy from the first day and then there was my 7 month screamer and my 4 month screamer. There is no rule, just do your very best, keep telling the parents what you need them to do to help or ask them about their routines and meet them in the middle.

And I agree with playfelt about getting complacent with an older group, then they go off to JK and you have to start over with babies and you are all out of practice. It takes lots of patience, and if the parents are with you, you'll get there.