“Before” stepping on the stage and dancing in a new costume, it’s best to practice in it first. I even recommend rehearsing in a costume that isn’t new, if it’s a new routine.
I actually had a wardrobe blooper once with a skirt. It was one of my favorite costumes that I danced in several times. I was wearing for a new routine I was dancing to. The bottom on the skirt had a beaded trim. The trim of the skirt got caught in my hair during the floor work of my set. So when I stood up I gave the audience a big surprise.