Transitioning from breast milk to whole milk

I breastfeed my son (no bottles) and he turned one last week and I would like to start to gradually wean him off nursing and begin whole milk. He eats three meals a day with a snack or two and nurses about 4-5 times a day. He will drink water from a sippy cup (with my help to tilt it back). Today I decided to see if I could skip an afternoon nursing session and give him whole milk in a sippy cup and it didn’t go well. He made a disgusted face and refused to drink any more of it. Any advice on how to transition from breast milk to whole milk?

Also, can I start to wean him off of nursing even if he will not drink the whole milk or do I have to wait to wean until he will drink enough (16 oz or so). He eats 3 meals plus a snack or two and loves cheese (esp cottage) and yogurt, so does he get enough vitamin d and calcium from that🤷🏻‍♀️?