I do have two sets of bottles, the one says to ask pediatrician if it's necessary to sterilize before use. The others, i forget I don't think it says anything.
I do have a snack cup thing though that says to boil for 5 minutes before first use.
I guess I'll just sterilize everything to be safe. I also didn't know that you had to do it once.
Lots of moms I talk to do it before every use.