We date each new set that comes in. My daughter uses three of them for each months cycle so that she only has to sterilize once a day. She rinses/washes them out and sets them on the drying rack then in the evening before bed sets them in the sterilizer and turns it on. On month 4, she disposes of the oldest set. We do keep one set at our house (she's married now) so she's always got an extra incase it's forgotten. Actually, we have everything duplicated at our house for visits, Nebs, machine, & percussor, which makes packing for a weekend visit easier for her. On trips, when you aren't really going to lug around a baby bottle sterilizer, I taught her to boil a cup of water in the micro and place the pieces (depending on the size of the container she used to boil the water) in the boiled water.