Personally, I waited with my daughter to wean until she showed signs of being ready, which ended up being abough 18 months. Of course your daughter might be ready - only you and she really know. I could tell with mine that she was really only drinking with me as a comfort measure. By that point she was already adopting the sippy cup and getting plenty of cheeses and other things that she didn't need me any more.
Cheeses and yogurts are excellent sources for the calcium and the cheeses are also good for some of the fats. One of the reasons they suggest switching to cows milk is for the milkfats which help brain development.
We had stubborn issues with my son where he was unwilling to relinquish his bottle for sippy cups and then he would only drink milk in sippy cups and never anything else. My pediatrician suggested that I put sippy cups of water all over the house and just plow through and not offer anything else. I did tend to bail out at bedtime, however, and offer him a bottle (he'd been on formula as I had problems breastfeeding with him) at bedtime for a long while. When we were trying to get him to have milk from a cup, that was all he'd get at mealtimes - milk in a sippy cup, and he wasn't allowed to have any water until after he'd drank all the milk. We started with little one-ounce increments of milk and then boosted it up once he was starting to drink it. Nowadays, at 5 years old, he asks for milk with dinner all the time. I think he was closer to two years old when we did this though - as long as she's getting water to keep her hydrated and enough cheese, yogurt, and similar sources of calcium and milkfat, I wouldn't worry too much yet. You'll have an easier time switching her over in the summer - when she's hot and thirsty all the time. Then you could lace the area with sippy cups of juice for her and make the transition then.
Good luck!