The 18-month sleep regression might not show up right at the 18-month milestone. You could see it pop up around 16 months or even just after your little one is already 18 months. Sleep regressions often occur a month or earlier than the common regression milestones (4, 6, 8, 12, and 18 months).
They can also show up later than those markers as well. Since these regressions may not show up exactly on time, it can be hard to identify if your child is experiencing a regression. Monitoring them for the common regression signs above is the best way to figure out exactly what you’re dealing with.