My B is 22 months old and he still need to drink milk in the midnite.
Actually he is eating a lots (two bowls of congee per meal, + biscuits + fruits + vitasoy, etc)
And he drinks 14 oz milk before he still (around 9:30 pm), but he still need to drink 9 oz at 4 or 5 am.
I think if he wish to drink, just let him la.. eat more before he go to kinder, and gain weight. As most people said BB will become thin after they go to kinder.