We are 2 months dummy dry for DD 3 years.
For about one year it was only for bed. If she wanted it she had to go to bed. Which of course was AWESOME for bedtime. She did, and still does, take herself to bed. Then a couple of months ago 2 years 9 months we told her she could pick a toy in the shops but she would need to pay for it with her dummies, no more dummies etc.
We talked about it for a week so she really understood and told her she'd be a big girl, no nappies (recently TT), no dummies...built her up.
Then we went to the shops and she handed over 5 dummies (we'd done a very good dummy find) for a soft dressable doll, she chose it but we gave her choices and I figured she could sleep with this.
To her credit she never asked for her dummies when she was upsrt and I think it was because it was her decision. So I will be waiiting until DS is old enought to understand too. It was SO nice having something to make bedtime easier all that time. Especially when a new baby arrived.
GOod luck