Never say the words "I can't wait until..."
We all do it.
"Oh, this is great, but I can't wait until he's crawling/walking/talking/potty trained/not obsessed with sticking his fingers in the dogs' eyes, etc."
What we're really doing, though, is wishing time away.
"Let's hurry up and get to the next thing. This is cool, but I am impatient."
That colleague had lost their beloved child. They showed incredible grace and strength by being excited for and supportive of us, despite their loss. They gave us that advice because their own experience had put it in harsh relief.
We made a pact to never use those words. And we do not.
And you know what? Every second is a joy when you think that way.