I left the skirt the size and length the tutorial said to, so when I attached to the top, it was shorter as I desired. The skirt falls just above the doll’s knee.
I made the tank top, removing about 1 inch or so from the bottom of it. I cut the squares for the skirt and gathered it. Then I attached the skirt to the top, closed the back of the skirt, and attached Velcro.