Really it depends on the quilt. Sometimes I just go ahead and buy the backing when it needs a specialty fabric to set it off. But, the impromptu quilts from my stash are buy later backings for sure. Neutrals are a great backing and it is good to have on hand, but how much to buy? Only the, I have this one in mind and the size needed would be, is the ones I buy. It is hard to buy ahead unless you have a reason or the price is unbeatable.