السلام عليكم ورحمة الله وبركاته
Some time ago, I heard in a lecture that punctuality is about being amaanah (trust).أمانة
Whether its about being punctual to work, school, or even just meeting with friends, it is actually a form of amaanah. When we talk about amanah, it will actually leads to other ettiquetes in Islam such as keeping promises or being a leader/having any kind of post.
Amaanah is a "huge" responsibility that each and everyone will be accounted for. Sometimes, some things may seem like small matters to one's but if it violates with the "amaanah", it will actually trangress the limits of ettiquetes in Islam. A very simple example is in keeping promises. If it happened that we couldnt keep our promise i.e we promised to a friend that we will meet her/him but then we couldnt make it and didnt even try to make an effort to fulfill the promise, so we have actually taken lightly of an amaanah. Such things happen so widely in real life. Some goes with being punctual in our daily life.
One of the signs of munaafiq (hypocrites) are those who always break their promises. نعوذ بالله من ذلك.
Thats what I had gathered from the lecture. It is surely a reminder to myself first and foremost before sharing it to others.
Waaalaykummussalam wa rahmatullah.