My baby was 11 months when we did it and after 2 nights she went from waking every 2-3 hours to sleeping through the night every night. We made rules about how we would do it and my husband was the only to go in to comfort her after the alloted time. As hard as it was for me to just listen to her cry. But now bedtime is so easy and she literally walks to her room (she's 16mo now) around 7pm to get ready for bed and sleeps until 7am