not a moment to spare: o quje isso significa?

Imagine you have a friend who's always on time. No matter if it's raining or sunny, he always arrives at the right time and place. One day, you set up a meeting and he is surprisingly late. While talking to the ones that have already showed up, you say: I don't know what's happening. He always arrives without a moment to spare.

When you arrive at places without a moment to spare, it means you're just in time, without any extra time. You were shocked that your friend for the first time since you met him got late for a meeting. That's it for now. Take care!