I've never had a card that offered Global Entry or Precheck fee reimbursement because I don't pay $450 annual fees, but a generous reader with many, many more such credits than he could ever use insisted I use one to pay my Global Entry registration fee (thanks, SD!).
This being the federal government, all the Global Online Enrollment System, or GOES, requires is the credit card number and verification code of the credit card used to pay the enrollment fee; they don't verify the billing address or zip code of the credit card.
I have three regional Global Entry interview locations relatively close to me, but since I wasn't in any rush I didn't shop around and simply selected the first interview time available in downtown DC. It was months in the future, and I completely forgot about it.
After I rescheduled the appointment to yesterday, I diligently set up calendar reminders on my phone so I'd be sure to make it. I had a 2:45 pm appointment, and gave myself plenty of time to get there, arriving at 2:19 pm. By 2:39 pm, I had completed my interview and was walking out the door.
Maybe just show up?
As far as I can tell, the Global Entry interview appointment system allows one interview to be scheduled every 15 minutes at a given location. But at an actual Global Entry interview location, there are multiple agents working and interviews take much less than 15 minutes.
I don't know if there's an official protocol, and frankly I don't know if the agents know if there's an official protocol either: when I showed up at my interview location there was just a ratty paper book where you wrote down your name and the time you arrived. There's also a line for "notes," where people at my location wrote down their scheduled interview time or "walk-in," but that appeared to have been made up completely by the people being interviewed; there were no instructions to that effect.
This is an extremely common phenomenon, where the objects of bureaucratic indifference organize their experience so it makes more sense than it, objectively speaking, does.
Agents have access to an eclectic range of data
The first question my agent asked me was "what was the purpose of your trip to Turkey?" My totally truthful response was, "I was connecting on a flight to Budapest."
Then he asked me about my business, and I told him about this blog, so he asked me, "so is your travel for business?" My totally truthful response was, "I try to be scrupulously honest about only deducting legitimate business trips."
Only as I was walking home did I realize all he was asking me was, "business or pleasure?"
So don't overthink the agent's questions. Just say "business" or "pleasure."
The agent also asked me if I'd ever been arrested "regardless of the outcome of the case." I told him I had and he asked me if it was for a DUI (drunk driving). It wasn't (I don't drive drunk), and I told him so, and he told me that his system was showing him "some notes." It didn't keep me from being approved so I have no idea what his "notes" were showing him, but the point is, their system has more-or-less real-time access to criminal databases, so don't lie if you've ever been arrested for anything!