How many mL's of formula should 2 week old puppies drink per feeding?

My dog came down with eclampsia over the weekend so the vet told me how to bottle-feed her puppies. They've been doing fine so far but I'm just wondering, what's the minimum amount (in mL) of formula they should be drinking per feeding? I usually let them drink as much as they want or until they start fidgeting away from the nipple and try to snuggle in my clothes. Also, when can they start drinking formula out of a bowl/pan and how often do I have to feed them in the middle of the night (they're 16 days old)? Thanks.