Bess made this pink tutu for her niece Amélie (who is 16 months) for Christmas, numerous layers of tulle were gathered and pleated (there is a few layers of cream underneath), and then fitted to a silk dupion waistband and drawn in with elastic. Then, Christmas being Christmas and the bling level needing to be raised Bess added beads and sequins to the waist.
Bess used the formula of gathering the tulle to 7″ bigger than waist measurement which worked okay but for a skirt this small 5″ is probably enough.