S.H.
Do not give juice.
Babies don't need that.
Also, some babies do not readily take to whole milk.
So ultimately, you have to see how your baby responds to it.
Some babies need to transition to it. ie: part formula or pumped milk... with whole milk. Then gradually over time... increasing the whole milk proportions.
Some babies, will also reject any form of sippy cup, with milk in it, even if they take the sippy for other liquids.
It is because, this is instinct... milk comes from a "nipple." Thus, babies will drink milk from a breast or bottle. NOT a sippy.
So again, you have to see how your baby, transitions to it all.
Main thing being, that he gets adequate intake of milk/Formula or your pumped milk. Whichever you are using.
Also, if a baby is filled up with solids all day, they will not drink.
Again, DO NOT give juice. It is mostly a habit. Not a nutrient and not necessary.
We didn't give my kids any juice, until they were well over 2-3 years old and it was always watered down 50-50 with water.
Just give him water, if anything, and milk.