I've been using a ME Sandy bamboo at night but with the stuffing it is not fitting in the back for my 4 mo old 16 lb DD2. I have an MEOS i bought for DS 5 years ago and a ME Sandy terry/cotton large i picked up on sale never prepped. Looking at the ME sight it is not clear if these need multiple or just one wash to prep - anyone know? I can't even recall how I prepped the ME sandy bamboo 2months ago let alone what i did 5 years ago! Also says not to use oxygenated products but i regularly use oxyboost and bac-out - think this will hurt things? What about vinegar (every 4-5 wash usually)? Not anticipating needing to use them again after this LO. TIA!