My son is 18 month old and has had a dummy since he was 4 weeks old (introduced by the nurse when in hospital with late onset strep B)
He used to have it as and when he wanted it, now he has it only for naps and bedtime. After naps, once he has had enough cuddles and has woke up properly and is ready to go and play he knows that he has to give the dummy back. Same with when he gets up in the morning (however usually swapped for his morning bottle).
My main concern is bedtime as he has 5-6 dummies in with him so he can always find one in the night which helps him sleep through. On the occasions he does stir I go into him and lie him down again and give him the dummy. I don't know how to settle him if I take them out of his cot. Any tips and suggestions?