How early did you introduce cows milk?

My 7 mth old is still on the and I have just found out I am pregnant and am concrned about weaning. I have tried many times to get him to drink formula but he won't. He does however drink cows milk mixed with water. I know that the recommended age is 12 mths, but I wanted to know if anyone has done it sooner and how it went. I will be talking to my maternal health nurse before I do anything, I just wanted to hear from some mums too.