I tend to be really loose with the appointments I make with my players.
As do I. Which means "official time" +/- 15 minutes. Other than an "open house" shindig, like a graduation or other party, there are few socially acceptable reasons to not try to make it within that window -- preferably on the early/before start side. I consider myself horrible with time management and feel guilty if I'm more than a couple minutes late. Things happen:
abnormal traffic (if the freeway is generally busy, plan competently), the dog squats on the rug, the in-laws drop by, etc. Those things are the exception, though, and should be so rare as to disappear into the background.
When we plan a session, we agree on a rough time when we want to start (For example, around 18:00 till 23:00). We also agree on having diner together, and then they usually show up around that time. They may be an hour later, but they usually call me if that is the case. It doesn't really matter if they are a bit late, because I already have the whole evening reserved for D&D, so one hour later, or two hours late, it doesn't really matter. We'll start when they are all here. Fortunately they all arrive with the same car, so it's never just one person who is late.
This one makes sense. We will occasionally do a "guys' strategy game night" where part of the deal is pizza. Dining together is optional, but the expectation is that there's only an hour set aside for it. So, if dinner is at 5:30, the game starts at 6:30 (at least, we start choosing colors, etc. at that time). We aren't jerks about it, but it's completely disrespectful to mess with people's schedule on the back side -- get to bed for early work, work second shift, wife waits up, whatever.
Real life commitments go first, so people can be late due to circumstances, its fine. But, if one player is consistently late, simply because he doesn't leave his house in time, that should be addressed. It's a shame if everyone except one specific player always shows up on time, and you all have to wait for him.
This one blows my mind: This
is a real-world commitment. Sure, it's not as important as a sick kid, my job, etc. But, it's something to which I've committed and which my absence has a noticeable negative impact on others. If I can't commit, I shouldn't have. At the very least, I should be up front about having a volatile schedule (as per my one player that was working tons of last-minute, mandatory overtime).