I have no tips - the only way I "cope" is to keep myself to myself, know exactly when I need to be somewhere, drive myself (or my partner drives me) and get there on time. I can't deal with involving other people in my plans (i.e. giving lifts because I don't know if they'd be ready on time, or what might happen), I just cope by doing what I need to do, and getting to where I need to be, on my own. I do get stressed if plans change, but I just quickly edit my leaving and arrival times and breathe!
My dad stresses me out to the max every time we need to be somewhere. He could just say "be at x place for x time" but he never does. He hassles me, telling me the time I've chosen to leave is too late, and I'll be late, and there will be no parking, and I should just go with him (I prefer the control of driving myself), and what happens if I get a parking ticket if I have to park elsewhere. Bear in mind, I always choose a perfect time to set out as I overthink it massively, and I always make sure there will be plenty of parking options. He knows I have anxiety, yet he goes on and on and on at me for days leading up to going anywhere, spoiling whatever it is we're actually doing. At my uncle's funeral the other month I was going separately because I couldn't stay all day as I had to get back to work, and he spent ages saying I couldn't turn up separately as it would "look bad on the family and get people talking", and that I had to leave earlier. In the end I arrived 20 minutes before he did, leaving me with that long to overthink the fact I was about to be face to face with dozens of family members. A horrible situation, which I didn't want to give myself time to sit and think about! Anyone with anxiety knows how painful being talked about can be - but I'm 28 years old for goodness sake, I don't have to turn up to everything with my parents anymore. Drives me round the bend.