Yep, ours worked within 12 hours. I find that if I take it off, it takes about the same amount of time until the grizzles start too. It's not all in my head either. The other night, we had about three wake ups where she was really crying. I didn't know what was going on until I realised I'd taken her necklace off the morning prior and forgotten to put it back on. I put it on the next morning and the next night, no grizzles! They are pretty amazing things. Sounds like it's working for you and your DD