Showing up late tells people how much you value them before you even say hello.

Lateness communicates a ranking whether or not you meant one, because the other person spent that time waiting and you spent it on something else. Occasionally it is genuinely unavoidable and everyone knows the difference. What lands is the pattern: whether their time gets treated as flexible while yours is fixed. That reading happens before any conversation starts.

If you are running behind, send the message while it is still five minutes rather than twenty. Someone you are consistently late for is worth noticing on its own.