Hi Jenna's Mom!
Our ped. says that at this age, LOs s/b drinking not more than 20 oz of milk a day.
What I did to transition LO now 13 mos to milk was to make his bottles 1/2 formula, 1/2 milk for a week, then I just switched them all to milk the next week.
During that time, I offered water or diluted juice in a cup with meals, and was sure to keep a sippy of water out and reachable by DS during playtime, walks, etc.
After the second week, when he was fully on milk, I took away the afternoon bottle, and replaced it with a cup of milk and a handful of snack of some sort (whole wheat crackers, healthy cookies, cheese, etc.)
I found that replacing that bottle with milk and a snack resulted in more snack, less milk, which got us to right about where we should be with milk consumption. I also found that he started eating more solids as that bottle was gone. From everything I've read, at this age, they should be eating three meals and 2 snacks, as their appetite indicates. (I just keep offering food until DS starts throwing it at the dog...)
About a week later, I took away the AM bottle and replaced with water in a cup and a bit of fruit. Right around this time, we transitioned to one nap.
We still take an 8 oz bottle in the morning and one before bed, and I don't plan to change that as it's working. But we're off bottles during the day all together. All told it took about a month to make the transition, but we did it slowly and DS hardly noticed!