We've all been taught that being late is rude, or at least unthoughtful...but is it kinda rude to be early? ...friends were supposed to drop off their child for a playdate; they called and said they'd be about 30 minutes late, then showed up 10 minutes before the original time, making them 40 minutes early
I would say that five minutes early isn't a problem, and that 10 would be pushing it, but that's just a personal take on things; I was taught by my parents to be ready 15 minutes early for just about anything, which still leaves a 5-minute margin.
40 minutes is ridiculous, and see-sawing like that strikes me as inexcusable. It's enormously disrespectful to you, and to the fact that you *just might* have other things to do with your time besides make yourself available to their every sudden change in whim.
I can sympathize. I moved to a new state (new to me, that is) recently, and everybody around here is completely spontaneous. People show up randomly without calling to see if you have plans, windows within which "I'm coming over" can be 6-8 hours in length, etc. I've had dinner plans change from one restaurant, to another, back to the first, then add a person and relocate themselves to my apartment within the space of 2 hours on the night of... and I wasn't the one making any of those changes. Plus, people with extremely restrictive lifestyles and fundamentalist viewpoints see absolutely no problem with inviting themselves along on plans that did not initially include them, then demanding that other people accommodate their preferences (be said preferences dietary, or religiously-based social restrictions, or the desire to strike up offensive conversations).
It drives me absolutely nuts, lol.