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.
It might be strange to think of sleeping as a skill that does not come naturally. As a new parent, you’re probably so exhausted that you pass out as soon as your head hits the pillow. Your baby, however, doesn’t have this same ability yet. Although they spend a lot of time sleeping, they need to learn when to sleep (day vs. night) and how to sleep. Until they do, they need your assistance, which is why you (as you should) help soothe them to sleep at bedtime and comfort them when they wake in the middle of the night. Sleep training is teaching your baby how to sleep without any help from you - just like you’re able to fall asleep without anyone there to help you do it.
"My son is 6 months old and finally goes to sleep without a struggle! We thought the Ferber method was mean and that alternatives would be better. So we tried it all – Baby Whisperer, No-Cry Sleep Solution, Babywise, etc. None of it worked. Our son is an otherwise happy little guy, but every night and every nap was a battle. We'd spend hours trying to get him to sleep. We delayed trying Ferber until we'd tried everything else unsuccessfully. It worked after the first night! He wakes up better rested and happier (as do we)."
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.