Scale the waist smaller closer to what you want the final shot to look like on around frame 10 or 15. Then set up the sim and the waist will tighten up and settle a bit for the rest of the frames in the sim. Remember that 30 frames is only one second and like cloth moving in the real world you may have to allow more frames (time) to get a good drape.

That drastic probably isn't needed by the look of your render. Check the offsets. Your settings may be stopping the cloth too far from the figure. It looks like you just left everything at the defaults. You want the collisions closer to the figure. Set them in the first step when setting up the sim.