Does using the Uber app days before you need a ride improve your chances of getting a prompt response from a driver?

I'm on a Yahoo group of retirees who travel often, and who are concerned about getting a prompt response if they need a pickup for an airport ride early in the morning - like 4:00 AM. They are concerned that there might not be drivers around (town of about 20,000) at that time of the night.

Some have the idea that if they use the app to set up a ride days in advance, that will significantly improve their chances of getting a pickup when they need it.

I say, based on my understanding of the Uber (or Lyft) system, it makes no difference whether you tell them you need a pickup right now, an hour from now, or next month, nothing happens to summon a ride until some fixed amount of time before your desired pickup time (measured in minutes, not hours or days)

They think that by calling for a ride days in advance, they have secured a commitment from a specific driver for that time.

Who's right?