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How Old to Start Potty Training — in the Day? at Night?

Updated: Dec 28, 2023

At what age do you start potty training in the day or night?

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The way potty training stories filter around a playground or parents' group, you'd think for sure there is some magic to it.

I waited until she was this age and it just took a weekend!
No pull-ups at night? That won't work until your child is older. I think they grow into being able to hold their pee overnight.

Turning a year older and all the milestones that come it — when your child is two, three, four — brings lots of changes.

Is there some magic to timing potty training at a particular age? The question is...

How old to start potty training in the day (and at night)?

Here's what we know about how age affects potty training — in a simplified list.

(PLUS, while we're talking birthday milestones, read on for what has been such a sweet part of our birthdays since toddler age! I'm sharing my favorite find for kid birthdays.)

what's the magical age for when to start potty training
Is there a magical age when potty training (in the day or night) is easier?

1. In Oh Crap Potty Training we talk about the ideal age for starting potty training as the window between 20 months to 30 months.

Why this age range? It's for a few reasons. There's a lull in development after your child has learned how to walk, run, and move their body. But then looking ahead, as the child gets closer to 3 years old, they move into the age of individuation, which brings on MORE behavior that adds a layer of hard to potty training.

Keep in mind this doesn't mean you're doomed for disaster if you start earlier or later than this age range. This is simply the pattern where we see a sweet spot for how old to start potty training based on development.

Jamie talks through the Oh Crap Signs of Readiness and how wait till they're ready and age affects timing potty training.

2. In overnight potty training, what's the best age to start? (That depends!)

If you see a string of 5-7 dry nap diaper or night diapers, that is your golden window to drop the diapers (no matter the age.)

But if your child is 3 years old, you want to attend to night training because the bladder is forming by around age four (and you don't want it to form without holding and consolidating overnight or the chances for having a bedwetter go up significantly.)

In my potty training night guide you'll find tips for how to drop night diapers.

3. But my toddler sleeps in a crib. Should we still start overnight potty training?

In Oh Crap Potty Training, we recommend starting night training either before you start toilet training at night or at the same time as when you drop the night diapers. When you're overnight potty training, you'll want to have a small potty by your toddler's bed. And you'll want your toddler to be able to go the potty if they feel the pee.

In a crib, that's not possible.

Now in considering the age of the child, keep in mind historically for generations the milestone for transitioning out of a crib has hovered around age 2. Suddenly in the past few years, as a potty training consultant I'm hearing more and more preschoolers, 3-year-olds and even kids close to age 4 still sleeping in a crib.

And there are a few reasons why we see that transition lagging later can affect potty training — both with self-initiation to go pee in the potty as well as making the potty training night training process more difficult.

Lifting your child out of the low setting of a crib is hard on your body. So logistically, it's much easier to night train when your child is in a bed. You also can't expect your child to pee in the potty if they're trapped in a crib.

For more on why the crib to bed transition is important for helping to build autonomy in a child, listen to this podcast by Jamie. Yes, you want to avoid raising a tiny toddler dictator, but even more importantly, you want to lean in on helping your child build on their independence.

When a child is in a crib, they literally start their day needing you to pick them up.

For a toddler at the potty training age, you want them activating that independence to climb out of bed (which is another good pelvic floor movement for their body) and feeling like they CAN do things for themselves.

Climb out of bed.

Pee in the potty.

Poop in the potty.

I can do it myself.

The magic is in timing these milestones close together.


And now for the fun piece I wanted to share with you..

You're doing all the work of helping your toddler build up their autonomy, pee and poop in the potty, hold their pee's a lot of big things!

What about the sweet side of letting them be little and embracing the magic of this age?

Here's one tiny ritual that we have LOVED over the years and has become a special part of the kids' birthdays. As you can see, this is a well-worn book because we've referenced it a ton for ideas for birthdays over the years.

This is our Birthday Book.

Before bedtime on the eve of a birthday, I always read a few tales from the Stories section (changing the name to match my child's name).

I always give them the number of goodnight kisses for how old they are and read the little verse titled, Two Verses to Be Said the Night Before the Birthday.

We've always started birthdays with a walk downstairs (to the table where presents await!). And paper stars or hearts mark the birthday trail.

All of these simple, sweet ideas come from this book.

the birthday book

Now that my kids are older (and still want to follow all the same rituals), it's clear to me what will be a core memory.

It's not the particular toy I bought as a gift when they turned three.

It's not the way the icing looked on their cake when they turned six.

It's these little details on repeat year after year.

It's expecting to hear the birthday poem and birthday stories, start their morning with a birthday walk, and then poof, their birthday officially begins.

I also love the old school ideas in the Birthday Book for creating simple magic in birthdays.


  • reminders of birthday party games and activities by age (including ones I played as a child.)

  • Simple recipes.

  • Birthday traditions around the world.

  • Homemade ideas for decorations and gift wrap.

the birthday book

We've used the birthday book to be a part of marking each year, each trip around the sun, with a sweet sense of celebration. It's one of my favorite parenting finds.

With this birthday book, it feels like we're ushering in a new age together.

As Jamie regularly speaks on the importance of connection with your child — at every age — this birthday book is one of those tools that I've felt has brought a greater connection and consistency to every birthday.

And that to me feels like a bit of parenting magic!

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