M.,
I give my son two 8 oz bottles (one in the morning and one at bed) - he drinks a sippy cup during his meals and i offer it for his afternoon snack (he sits in his chair in the kitchen while i empty the dishwasher and get everything ready for dinner around 330/400).
we were giving him an afternoon 'before nap' bottle but we phased that out... actually... phased isn't the right term...i just stopped giving it to him one day, and he didn't miss it :)
so for now, i would say 3, 8 oz bottles is probably about right for 12 months, but try to push the sippy cup (if he isn't keen on it quite yet - my guy needed a bit of time to understand that it was more than a play-thing that makes a huge mess), and work on getting him down to 2 bottles for about 16 oz. - i should add... though i 'offer' 8 oz.... he doesn't always drink it all.
something that i have to work at and remind myself a lot though... during the summer months, they do need to drink water, or some other fluid (i say water becasue it's better for the teeth) to help rehydrate...and to keep from overheating, so i would suggest starting now to introduce water in one of his sippy cups.
good luck! Congrats on your son turning one :)