how to stock up on bottles


So I used to work at a daycare and I'm very partial to Tommee Tippee so that's what we have bought for a couple bottles and pump & go sets. My sister made the comment yesterday "better hope he likes that brand"...i get that not every brand works for ALL babies but how on earth am I supposed to get prepared if that's my mindset? I like to be prepared so I'd probably die on the inside a little if I have to wait lol