To begin with, the stimulus was $787 billion, not $800 billion. (Those of you who think there isn't much of a difference, please make out a check for the difference to Daniel M. Gross.) The more egregious error has to do with the timing. Many critics act as if the entire amount has already been spent. They're completely wrong. Even to argue that it's been half-spent, as the Post, does, is only half-right.