Originally Posted by
1KChinito
You can use Global Entry kiosk once you have received final approval without physical GE card in hand. Your passport is linked to your GE.
Just to clarify that point a bit further: final approval means you went in to the Global Entry interview and were approved. I believe you also receive your PassID number which you could then plug in to your profile with UA and other airlines to ensure you get the pre-Check mark most of the time (getting a pre-check mark is not a guarantee since it's a random process for "security" reasons). However, you'll want that physical card when crossing a land/sea border (i.e. Canada into the US). It is also useful when travelling domestically since the Global Entry card is considered RealID for the purpose of TSA so if you're in a state where your driver's license isn't RealID complaint then you can use the Global Entry card.
-James