Too Old for a Bottle?
Mothers are often advised to get rid of the bottle by a year or 18 months at the latest, but I think 2 is plenty of time. It’s not the end of the world if your baby takes a few minutes at bedtime with his bottle to snuggle up in Mum or Dad’s lap.
Left to their own devices, many toddlers give up their bottles voluntarily by 2. When they want to hang on longer it’s usually because they’ve been allowed to use a bottle as a dummy—for instance, Mum gives it to him as a quick fix to shut him up at the mall, or Dad shoves it into his mouth to avoid a meltdown in front of company. Or the parents may use a bottle to send him off to naps or nighttime sleep. Some parents leave a bottle in the child’s cot, hoping to grab an extra hour of sleep, which is not only habit-forming, it’s dangerous. The child could choke. Also, when a child is allowed to nurse a bottle all day, he fills up on liquid and often eats less food.
If your child is 2 or older and is still walking around with a bottle, it’s time to intervene:
**Make some ground rules about the bottle—only at bedtime, or only in the bedroom.
**Bring snacks with you, instead of relying on the bottle for sustenance, and deal with tantrums differently.
**Make the bottle less attractive. Cut a slit in the nipple, about 6—9 mm (1/4 —3/8 inch) across. Wait 4 days and then cut a slit the other way, so you’ll have an X. After another week, cut first 2 and then all 4 of the triangles. Eventually, you’ll have a big square opening and your child will lose interest altogether.
taken from "the baby whisperer solves all your problems" p 127