I adhere to the 12 month rule. I think it's easier to get rid of the bottles at that age and takes less time to wean them. I don't use sippy cups. As someone else mentioned, they are not good for the child's mouth. Not only speech therapists, but also dentists recommend against them. Straw cups are fine, but I train my daycare kids to drinking from regular glasses as soon as possible. I start at about seven months, depending on the child's development, with a juice glass. I use the little juice glasses that you get Kraft spreadable cheeses in, because they are sturdy and small enough around for the child to try to hold. I use only water to train them with the glass and give just a few sips several times a day. This gets them used to the new way of drinking, and most of them are anxious to begin holding the glass for themselves. It takes about two months before I'm ready to actually let go and let them do it all on their own. By the time the parent is ready to wean the child from the bottle I have the child ready to drink water, mild or juice from a glass or cup on his or her own... with close supervision of course. '
By the way, some of you may be cringing that I use container made of glass because of the problems that might come from breaking them. I am old enough that glass was the only choice my mother had other than those nasty aluminum cups that left a metalic taste in one's mouth. While I do have some plastic cups for the children to use in certain situations, we use real glass (sturdy ones of course) at the table all the time. We've had only two glasses broken by children in over two years of caring for children in our home.