Introducing cows milk

My son is starting to not want anything to do with his bottle. He is almost 11.5 months old and basically eating anything and everything we eat. He’s already weened himself off of his afternoon bottle so my question is would it hurt to introduce cows milk? It’s a lot cheaper than the formula I’m buying and that he wastes. He’s only a few weeks away from 1 so I figured he’s be fine, but I’m a FTM so I’m not 100% sure. Also, how do you introduce cows milk? Do you mix some of the milk and formula or just put some in a sippy cup? He is amazing with his sippy cup. Thanks in advance for the help.