In considering other effects, I'm guessing that you're wondering if the smoke causes creatures breathing difficulty or something along those lines. However, the text states only that the smoke obscures vision, so I'd say that's the only effect it has.
As for the immediacy of the effect, again the text states that it obscures all vision in a 50' spread 'in one round'. I'd rule that as being one round from the point at which a character opened the bottle, to just before that (N)PC's next turn. Thereafter, the spread extends by 10' per round until it reaches its maximum or is sealed (other effects, such as wind, notwithstanding). I'd measure each increase to the area of the spread as taking effect just before the activating (N)PC's turn in each subsequent round.