My girls were 1 and 3 when I was dx. Ive never sheltered them from this. I had one more child, a son, after my dx. They have been raised knowing, and therefore knew from early on that mama cant always do the things I wanted or that they wanted me to do. IMO, its best they know young, but in their language, age appropriate is what I mean. Someone mentioned the books from NMSS and its a great idea. They give you alot of info on how to tell the wee ones. Its very helpful and free.