I call as soon as I arrive because many pax aren’t even looking at the app while you’re driving up, so they don’t always know you’re there. I call and say “Is this Jeff? This is ----------, your Uber driver. I have arrived and waiting outside.” I also assume it helps them to come out quicker than if I did not.
If the surge is big enough I’ll try to secure the fare. I’ll still call and even multiple times if they’d ont answer(usually it’s post bar closing hours) If they are just taking too long and it’s still surging I’ll give up and try to find another. I don’t mind waiting during big surges because I drive XL and its common for me get $100 or more fare for short mileage. Of course, you never know.