I sanatized them if they were brand new and then sanatized them every other feeding. If you have a dishwasher there should be a sanatizer setting that works great for bottles and nipples or you can buy bags at the store that you put water and nipples in and stick it in the microwave... easier than boiling them.

I sanitize every other day. Or ill let 2 days go by. But I use hot soapy water.