What I typically do, just to stay on the safe side- cut the top of the bag open and poor her into a small cup, so she has access to fresh air. Float the cup in a heated tank to let the temperature in her bag acclimate. Then after about 20 minutes, fill about 15% of her cup with your tank water. Then let her sit for another 30 minutes. Put another 15% in, let her sit. Do this until the majority of the water is tank water- it's time consuming, it takes several hours, but it's the best way to ensure her system doesn't get shocked. I think it's less stressful for them to have their water level increase in small amounts, rather than going from little cup to big tank.
It also ensures that she adjusts to the different chemical properties in the water.
Popcorn! How cute. =D Mmmm... mold on popcorn can be blue, right? :P