Toward One isn't an explicitly short-form game, relying on the RPG-audience's assumption that any game that doesn't say otherwise is a campaign-form game.
Players will be defeating Jinn and taking on new ones, improving, conspiring against each other, and so on each at their own pace. Play continues until, quite literally, the game ends: in particular when the time allotted for the session is over, and in general when the group wraps up or drops the campaign.
A good victory condition would be when someone says "that thing you're about to do is awesome and clearly we are now in the endgame of these people's story: let's do this!" and then you do it.