Last week, in a clash of finite patience and unnecessarily sodden pull-ups, some words were said between my wife and my son. I don’t know what these words were. I wasn’t there, and I haven’t asked for details. The important thing is that Ian decided to become a Big Boy, and that no longer would he need a diaper. And he hasn’t.

We spent Easter weekend in Des Moines: a six-hour drive from St. Louis, and nary a wet diaper. It was a weekend of dry nights, dry days, and the diaper bag intentionally left behind.

‘Did you grab his bag?’

‘Nope.’

And there was no sense of dread, no rising panic, no last-minute inventory of the weekend’s supply of pull-ups. Again and again, there was only the sweet sound of my son’s voice: ‘I have to tinkle.’

I was sure the return trip would cause Ian to stumble. We took the long way through Kansas City, to avoid afternoon storms along our regular route, and we left late in the day. A seven-hour drive, with Daddy in a hurry and reluctant to stop. The test had begun.

Ian fell asleep at once. Hard. He woke two hours later, ankles crossed. ‘I have to tinkle.’ One nice thing about being a boy is that, in a pinch, the world is your bathroom; especially when the Next Rest Area is twenty-six miles away. One more stop several hours later, and we arrived in St. Louis with the tell-tale planets still visible on Ian’s Toy Story pull-ups.

In my vicarious browsing of other parents’ potty-training experiences, the common factor always seemed to be that success was by choice alone; and so it was with Ian. Until he made the decision use the toilet, all we could do was encourage, wipe, and wait. And wait. And wait.

It’s easy to be over-confident, and I’m sure we’ll have an accident now and again, but in the meantime we’re so, so proud. Ian’s proud, too, and I think that’s the neatest part. He knows he’s being responsible, and knows that it’s important. We’ve been giving him two M&Ms for a dry diaper, but this weekend he didn’t ask for them. Arms raised in triumph, pants around his ankles, Ian shouts, ‘I go tinkle!’

My mother-in-law says that she recalls her daughter’s last diaper change as bittersweet. It was a milestone, but those special, intimate bonding moments between parent and child were gone. I’m keeping an eye out for the bitter, but for now all I know is that our house hasn’t smelled this sweet in three years.