When you start mixing BM and cows milk to transition over to cows milk - do you still warm it up?

My daycare is encouraging me to go cold turkey and switch one bottle for cows milk but my daughter is drinking less than an oz. So I am thinking of back tracking to doing the 3/4 BM + 1/4 cows milk and then increasing ratios of cows milk plan that I've read about on here. But I'm wondering how the transition happens so she doesn't always need warm milk...

THANKS!