On March 31st Pondertex posted this same type of question check it out.. Here was my answer.. You could give your child this weekend to switch over..
At about 11 months, I started telling our daughter the bottle will go bye, bye on her first birthday.
I took her to the store and let her pick out the one she liked. I also purchase a couple of other styles in the same form. I kept them on the kitchen counter so she could see them. When I would prepare her bottles, we would talk about the big girl sippy cup.
The night before her birthday, I reminded her that in the morning, she was going to "get to use the big girls sippy cup."
I threw away all bottle paraphernalia and had the sippy cup on her high chair. I asked if she wanted juice or milk? She said milk.. She took the first sip and her reaction was 'Ooo!" that day at her birthday party lots of people included sippy cups in all varieties.. From then on I would ask her which cup and she would point to the one she wanted.. I also let her pick th eone for her diaper bag, so when we went out, she knew that was the "diaper bag cup"..