For a one week old? We occasionally supplement at night with formula due to pain from poor latch due to posterior tongue tie. She usually takes 0.5-1.5oz max. I'd rather offer her expressed milk. I don't want to offer too much and waste it. Supplements are usually top ups rather than full feeds as I know night feeds are important for supply.
well, my LO in the first week was eating between .5 ounces to 1 full ounce. I'd had issues with my supply in the beginning so I'd almost cry when there was milk left in the bottle that I'd have to toss. BUT I think you'll have to just bite the bullet and see what he eats in the beginning then feed accordingly. Also be careful because with a bottle sometimes they'll just eat to eat because it's such an easy flow into their mouth. So if he spits up often afterwards, it's probably a little to much and I'd cut back a smidge. (in the beginning of the 1 week mark it was .5 then about halfway through he was at 1 full ounce) Hope it helps, drove me nuts that there was no guide for breastmilk bottle feeding always worried about starving him or feeding him to much. Good luck!!