M.I.
Im in the process of doing that right now also. I started by giving my daughter 6 oz of formula and 1 oz of whole milk. then after a week I gave 5 oz of formula and 2 oz of milk, then a week later 4 oz of formula and 3 oz milk, then the 4th week 3 oz of formula and 4 oz of milk, 5th week 2oz of formula and 5 oz of milk, the 6th week 1 0z of formula and 6 oz of milk and then finally the 7th week it was 7oz of milk. Her Dr said its a gradual process, if you do too much at a time they will not drink it, plus there stomach needs to process the change. With my daughter she had problem processing the proteins in milk and is lactose, but this seems to be working, Im on the 5th week now and she is doing great, but also my daughter will eat anything ( except eggs) which she is allergic too, but try this and see if it works.
With the juice, well I wouldnt give her much it has a lot of sugar that will make there teeth rotten, but if needed and water to the jusice, whenever I give my daughter juice I give her half juice to half water and it works like a charm..Hope I can help