Most experts recommend starting when your baby is between 4 and 6 months old. By about 4 months, babies have typically started to develop a regular sleep-wake cycle and dropped most of their night feedings. These are signs they may be ready to start sleep training. Many babies this age are also developmentally able to sleep for long stretches at night.
Thank you for your comment! We agree, and we think most parents do, that cry-it-out is a last resort, and we always recommend trying a gentle sleep coaching method first. That said, the research on cry-it-out is that, done correctly and not as a replacement for parenting your baby, it is not harmful, and can indeed be beneficial when you consider the damage that lack of sleep can do to a baby’s overall health and well-being. We have an article with further information about our philosophy on cry-it-out here: https://www.babysleepsite.com/sleep-training/cry-it-out-age/
Once you launch your plan, stick to it. Parents who've been through sleep training agree that consistency is the key. Unless you realize that your child simply isn't physically or emotionally ready and you decide to put the program on hold for a while, follow through with it for a couple of weeks. When your baby wakes you up at 2 a.m., you may be tempted to give in and hold or rock him, but if you do, your hard work will be wasted and you'll have to start over from square one.
There’s not an exact time that we can recommend, as all babies are unique and it will depend on how tired baby was, how much sleep they got that day, etc. Ou recommendation is to be sure baby falls fully asleep. You can also try working on your bedtime routine if baby is waking up fussy—white noise and dim the lights 20 min before bedtime. bath time, etc.
There’s also no need to institute a regimented cry-it-out plan if what you’re currently doing is working for your family. But good sleep habits never hurt, and being able to fall asleep on one’s own is a necessary life skill. If you sleep-train at a time that’s developmentally appropriate for your baby and with the basic ingredients of healthy sleep in place, you can minimize the amount of crying your baby (and, let’s face it, you) will do.