Someone said this to a young soldier a long time ago and it spread because it’s true. It sounds like a military thing. It isn’t. It’s a character thing.
When you are late you are telling everyone in that room that your time is worth more than theirs. You may not mean that. It doesn’t matter. That’s what it says.
When you are early you are telling them something different. That you take this seriously. That you can be counted on. That you respect them enough to be ready.
What being first actually does
You get to set yourself up. You get to breathe. You get to look at the room before the room looks at you. You get to meet people before the pressure of the meeting starts. You get to be calm when others are rushed. The person who walks in at the last second is already behind. They spend the first few minutes recovering instead of contributing.
The compound effect
Reliability is built in small moments. Nobody gives you a trophy for being early. But people notice. And over time, being the person who is always there, always ready, always on time becomes part of how they think of you. That reputation takes years to build and one bad habit to erode.
The practical part
Add 15 minutes to whatever you think it takes to get somewhere. Account for the thing that will go wrong, because something always does. Leave before you’re ready. Arrive before you need to.
Do this long enough and it stops being effort. It becomes who you are.