Ds could drink out of sippy at 7 months old, hold a mug at 10 months and drink from it and use open cups at 1 yrs....BUT only water. Milk in his world only came from a booby or a bottle. I was fine with it as he could drink from other things, didn't walk around with a bottle hanging out his mouth and we brushed his teeth (had 16 teeth at 1 and all including 2nd yr molars at 2 yrs.)
He weaned from BF at 19 months (his choice). He weaned his bottle (was only having one after supper) at 3.5 yrs.

He is/ was my baby, I saw no need to make him stop from his beloved bottle, he walked at 10.5 months, asked to go to a big boy bed at 26 months, was completely toilet trained (day and night) at 27 months (he initiated) so if that was his one connection to being a baby and wanting his "milkies in his bot-bot" god bless him. He has always been a child that knows what he wants and has fabulous self control, so he had a bottle until he was 3.5 yrs old, big deal.
His favourite drinks to this day are milk and water. My 2 cents / pence.
