I have a 19mo son who was very difficult to wean onto a sippy cup, in fact he was around 15mo before e could get him to use one, i bought a total of 7 different ones before i found on he liked, but he still has his bedtime milk from a bottle. He wont drink it from his sippy at night time, and he takes the bottle as his cue that its bedtime. After his bath, he is changed into his pj's, has a story then its milk and bed. I dont see a problem weaning him off this bottle for a while yet, it doesnt seem to do him any harm and as i say he knows that its the last thing to happen before he is taken to bed.