My daughter, 5 years old, used Nipit to quit sucking her thumb in one week, although I kept her wearing it for another week to be sure. We put it on right after teeth brushing after dinner and left it on until morning. She needs my help getting the velcro straps on/off because she hasn’t developed finger strength or dexterity, but an older child should be able to get the straps on and off themselves. Make sure the cushion pad is on the Inside of the elbow crease.
She had a difficult time falling asleep the first two nights as she couldn’t bend her arm all the way. If your child resists wearing it in the beginning, you might try putting it on after they are asleep. After the second night she saw that it was helping her and developed a level of comfort wearing it; she found that sleeping on her back or with her hand above her head was the most comfortable position.
She was really motivated to quit. Her big sister teased her and so she wanted help. We made a two week plan and agreed on a buying her a craft kit she wanted if she could not suck her thumb for 14 days. Each morning after a successful night, we put a smiley face on the calendar so she could visually see her progress, and I gave her a small reward – either a quarter for the piggy bank or just a promise of extra dessert. And I gave her praise whenever I saw her relaxing without sucking her thumb, when she previously would have been.