The next step is to wait, making this a good learning opportunity for a preschooler. If you don't wait, or don't wait long enough, the pretty polish will rub off. Waiting is good.
Another learning opportunity came out of this, too. In the time it took for me to set my camera down and pick up a bottle of polish off the floor, Purple had swiped the other bottle of polish, made her way to another (carpeted) room, and was in the midst of applying a thick coat of the glitter polish to her fingernails. Purple has a streak of stubbornness and was not about to give up on the glitter. I quickly guided her back to the other room containing hard, flat surfaces, and provided a scrap paper for her to rest her wet nails on while I painted her other hand. Whew. I learned my lesson.