The time to start sleep training is 1) once your child is at an age when they are capable of soothing and regulating themselves. I start working with families at 18 weeks at the earliest. And beyond that 2) when whatever you are doing to help your child sleep is no longer working for you, your child or your family. That is to say that if whatever you are doing is working then far be it from me to say that it is a problem.

As far as too late, I work with children until they are 10 years old so these are certainly things that are still changeable into school age years. These sorts of changes don’t necessarily get easier to make though as children get older.

As far as timing, it isn’t a great idea to be trying to make changes that require a lot of consistency in the midst of anything that might be disruptive. Potty training could be one of those things, visitors who are going to make consistency hard, an upcoming trip (within the next 2 weeks—especially for toddlers/older children), a move or the imminent arrival of a sibling.  

A sleep crutch or sleep association is anything you do to or for your child to help them fall asleep at bedtime and then often back to sleep overnight.  Some examples of sleep crutches are feeding (nursing or a bottle), holding, rocking or bouncing to sleep.

For children who are in a bed, the most common sleep crutch I see is when parents are laying down with their child to fall asleep at bedtime and then again overnight or co-sleeping whether it is at bedtime or throughout the whole night. Newborn babies and children under 4-6 months often need help falling asleep at bedtime. This is normal and to be expected. Often those things that we do to help our children fall asleep will stop working at some point in time.

Just like in my answer to the question above, a sleep crutch is never something that is a problem until it is no longer serving you. In some cases, sleep crutches can continue to work as children get older but it will take longer and longer to coax a child into sleep as they have more capacity to stay awake for longer periods of time.  In many cases, whatever you do to or for your child to help them fall asleep, they may need that much and more as the night goes on.

Sleep regressions are absolutely real. Some children experience more regressions than others. This can often be related to your child’s temperament and how sensitive they are to things that are both changing in their body or things that might be changing in their environment. Sleep regressions most commonly are correlated with periods of developmental change/growth. The big ones are at 4 months (burst of developmental awareness, rolling, growth spurt), 9 months (separation anxiety, learning how to pull up to stand), 12 months (walking), 18 months (language developing very rapidly), 2 years (more language development, words having more power), 2.5/3ish (moving from a crib to a bed).  

Regressions can also be brought on by travel, illness or teething—times when parents end up not being as consistent as they might be otherwise, especially if these inconsistencies persist beyond when the disruption resolves.   

In the early months, when you are in the trenches, know that this is normal. Hard, yes, absolutely. I would never minimize how difficult those early newborn days/months can be.  

It will get better though, both when your baby is at a developmental stage when they are capable of doing more independent soothing and regulation and their brain is developed in a way that enables them to sleep better, but also when they are at an age when you can make more significant changes.

Honestly, my strongest recommendation would be to stay away from the internet and social media that makes it seem like you are doing it all wrong and everyone else has these things figured out. And see what kinds of supports you can put in place while you need them.

This may be parents taking shifts throughout the night in order to help each parent get some longer stretches of sleep at a time (heads up that the short end of the stick shift is the early morning when sleep is the least consolidated for newborns)—this can be done even if you are breastfeeding, having family or close friends provide respite either at night or during the day to help you recover a bit or possibly a few nights of postpartum doula support. I promise, this is not forever, it can get better!

My advice would be to help your child, at the very least, learn how to fall asleep independently at bedtime. This is often the key to the whole night. About 80% of all children will eventually sleep through the night once they have fallen asleep on their own at bedtime. It can certainly make a big difference.