My daughter is 16 months and i have had her using cups, sippy cups and bottles since she started cereal. It is much easier to go through the transition from bottle to sippy cups because they have cups that are in between. Ones that are like sippy cups but have the soft mouth piece, theres not very much different but it helps your baby along. Try Nuby brand cups. I got mine at walmart for a couple dollars and I will probably use them for a while. :)
Well it was easy for me to switch my daughter over.I began giving her a cp during the day and her bottle @ night.She must of gotten used to the cup because a week later the bottle was no longer needed.This was @ 6 mths.
As soon as they can hold and put the sippy cup to their mouth give them the ones with the small holes to use as much as possible ( I started after they could sit really well). Let them use it as much as possible. Only give the bottle before bed or naptime if they want it. Will be so easy to break them from it then. All mine (4) were completely off bottles between 10-12 mo.
Whether you work up to it, or go cold turkey, it really doesn't matter--both have potential for problems...the most important part is to do it as early as possible (and developmentaly able)--the longer you wait, the harder it can be.