In Ron Edwards' writings on GNS and the Big Model, the characteristic phrase of Narrativism. Narrativism is defined as the category of Creative Agenda "in which Premise is addressed through play;" Edwards uses "Story Now" to distinguish Narrativist goals from what he calls "Story Before" (in which thematic decisions are all pre-made, usually by a GM) and "Story Later" (in which play itself doesn't address theme, but themes can be inferred after the fact).

(Note that "Story Before" and "Story Later" are not generally used as terms in their own right. Also, Edwards has gone on to use Story Now as the name of the game system/"group leisure activity" described in his book Spione; that system should not be confused with the general term.)

References:

• Narrativism: Story Now