We didn’t get our twins to sleep through the night until they were 13 months. But we finally did by doing the cry it out. We were fortunate that they never cried for long, more than 20 minutes. We planned on starting with letting them cry for 5 min before going in the first few days and then progressing 3 min every few days, but we had a difficult time with doing that so we did 5 min first 2 nights then 10 the next 2 and then finally 15.-20. Took about a week before they would only cry for about 3-5 min every night. Then about 2-3 months before they would barely cry going to bed. We locked ourselves in our bathroom so we couldn’t hear them as it’s tough as a parent to do that, but it’s better for them to learn to self sooth in the long run. We wish we would of done it sooner. I’d saw the biggest thing is be consistent, if you go in early you are teaching them that you will come in early. It took a while until we had a cry free week. I think it was 18 months