Lo is almost 6 months old and is only eating 4oz at a time. If your going to do formula you really only need one bottle that you can rinse between feeds and wash fully at the end of the day. LO takes BM mainly through a bottle i only store 4 4oz bottle at a time and then freeze the rest. So you probably wont even need the big botles till much later. I may use a big bottle for pumping and storing, not for feeding.