H.B.
we started the transition from formula to milk at 11 months.
I would mix the formula with the water as usual but then add milk. so the first week I did it I did 3/4 bottle of formula with 1/4 bottle of milk, then 1/2 and 1/2 then 1/4 formula and 3/4 milk and by the time he was a year old he was on whole milk all the time. in the beginning it seemed the whole milk wasn't filling him enough at bedtime so for about a month after he started whole milk I was giving him a bottle of formula at bedtime