stuff it, the more it sits up the creases will come out over time. the more you use it, the less time it will take. this should take about 2 weeks or so.
Just use it. Whenever I get a new LV, I try to use it as much as possible so that the creases come out faster. The more you use it, the faster they come out.
i actually love creases on my speedy!! i fold them whenever i'm not using them so they get the creases again. i love how the creases give my speedies a "new bag look" hahah. anyway, just don't fold it again...creases will disappear in no time.