DH & I applied for our Global Entry cards in late Nov. '19... No appointments then for months out - so we figured we would "just wait" until we returned from the next trip - mid - 2020... Ha!
Every time we looked for appointments - all were booked months in advance.
Last week - he figured out the trick: Must say - one of the GE staff said "look daily - lots of appointments are cancelled." Airport map (online) should show where the GE office is - TPA's is at the end of "red" baggage claim - and is separate from TSA-Pre and the other entry options.
Here goes:
Book an appointment (ours were for mid - October for Tampa airport). System will send you a text w/validation number every time you sign in.. kind of a pain - but I give them ++ for security effort.
Sign back in and look at "your" account
Check Reschedule Appointment box.
Fill in the reason (we said - Need sooner).
When the calendar appears - tab back through the months - from Oct to August... If there is an appointment the date will show. The calendar will not let you search backwards until you have an appointment scheduled.
He looked on a Thurs (7/29) and found one for Mon. Aug 1 - 7:45am.. They wouldn't take me (each takes a separate slot).. I looked on Tues (8/2) early and there were 2 available for that morning. Neither were there on Mon. afternoon. I picked the 10:30 over the 8:30 - figured PJ's would be frowned on ;-)
If you don't see one available - just sign out - you don't loose your original appointment. And keep on trying!
Received our GE cards in the mail today (1 week).
Note: He flew to CA 2 days later and took advantage of the TSA approved status - even without the card (account # was already updated & that's what United's system wanted).
I know some don't live as close to their travel airport as we - but if you do and are still battling for an appointment - Hope this helps.