I started to give DS2 (who turns 1 in 2 weeks) cows milk - straight, in his cereal/weetbix a couple of months ago and then over the last couple of weeks I have been giving some in a sippy cup. Over the last week or so he has really been loving it...finishes the whole sippy cup now...which works out well as I'm about to return to work next week so BF will be only available morning, evening and through the night. But I found with DS1 who was on formula from about 10.5months that it took a little longer for him to drink cows milk straight when offered around 12months...so I bought an extra tin of formula - which saw the month out....I always offered the cows milk first and really only used the formula for bed time....he eventually after the month got use to the cows milk and didn't have to buy another formula tin after that.

So maybe just put some in a sippy cup when your giving him breakfast, lunch and dinner...he'll might just play with it at first then realise its quite yummy.

Good luck with the transition.