Hi C.,
As a dental professional, I recommend weaning from the bottle completely at a year. Bottles are TERRIBLE for teeth, especially at bedtime. I bought my daughter a special sippy cup that was only for before naps and bedtime. Only water goes in it. At night, brush his teeth thoroughly and only give him water afterwards. It took my daughter 3 or days of asking for milk before she got the hint. I timed it so that it took place the same day she saw the dentist for the first time. I had the dentist tell her that she had to have her teeth brushed before bed and then could only have water afterwards so her teeth would stay clean. Whatever you do, don't give in. Forcing them off the bottle isn't bad, it is actually very important and this will be the first of many things you will be "forcing" him to do for his own good. Early childhood caries (cavities) is on the rise in the US, so doing everything you can to minimize his chances of caries is important. Expect some fussing if he is attached to his bottle but be strong. Email me if you have any questions.
Sincerely,
L.