With all of the information that’s available online, and the advice of your friends and family who have managed to get their kids to sleep, why would you want to invite a stranger into your home to get your child sleeping through the night?

This is a difficult question to answer without getting into some specific details, which is unfortunate, because when parents ask me this, I know they’re looking for a quick, concise, time-based answer. “Three nights from now,” or “Six months old,” are the kind of responses they’re hoping for, and the kind I wish I could give them, but there are a lot of factors to consider, and some things to understand before you can narrow down the timeline. The first thing I feel parents need to understand is this...