With DD once my milk came in a couple days after delivery I made enough milk to pump and freeze at least 5 oz per side in-between feedings so it doesn't always take weeks to establish supply. Every woman is different, so you may make plenty this time around. This was great because I built a nice reserve but I learned it can also cause over-supply issues. Lots of good forums about BFing issues and tips on LLL site, too. As for milk bags - I did both bottle and bag depending on which bags I had on hand. I have a Medela pump like the Lansinoh bags best because as PP said, they freeze flatter. But the Medela has a little attachment where you can hang the bags and pump directly into them without holding on, which is convenient. Pumping into bottles works, too, but I like to wash fewer things!