We switched to whole milk for them at 12 mos and then at 2 they went to 1% which is what we drink.I waited and started at 12 months. For the first week or two I mixed the formula and milk. I started out with 3/4 formula 1/4 milk, then went to 1/2 and 1/2, and so on. Everything went smoothly.
My friend switched her son to milk totally, the day before leaving on vacation because she did not want to have fool with carrying and mixing formula. We both used powdered Well, the kid ended up with severe stomach cramps and diarrhea. The 4 hour plan ride was not fun!!
You can actually start cows milk in cooking and on cereal from 6 months. I think I went over to dd drinking whole milk at just over 11 months as I had finished a can of formula and wasn't going to buy another one for just 4 weeks. Their digestive system doesn't suddenly mature at the magical 12 months so as long as they are a good size baby then 10 - 11 months should be OK. I wouldn't personally do it much earlier than that.
Gotta love MIL's 
I was so picky I made all of her food, and it all had to be organic. My how things have changed!
i waited until 12 months for my DD. But I took her bottle at the same time so all she got in her sippy was cows milk. WHOLE. My DS, the same. Binkys are a whole different story though....LOL
It is finally gone.when you say cup - do you mean sippy cup or regular cup? DS is 10 months and he has trouble with the sippy cup and really uses the bottle mostly.