I usually use ExpertFlyer to look up a future date's departures from an airport

But given how Saturday = tomorrow, I'm gonna use FlightAware, instead, because I just need to click "next page" a few times and then I'll see the Sat scheduled departures:

https://flightaware.com/live/airport...etime;sort=ASC

(click previous page to go up if you're viewing this hours after I post this msg)

I see the Denver, Phoenix-Mesa, Nashville, and San Francisco flights in the first hour (from 0610) scheduled this Saturday. I have no idea how full those flights are, but from my pre-COVID experience from the 0700 DL departures YEG used to service, Preclearance was fast-moving but quite crowded at 0600.

The CBP website says the Preclearance facility opens at 4:30 AM (if they even bothered to update these hours recently), which will shoe in the "I-need-to-arrive-at-the-airport-three-hours-early" crowd into one big mass. Since 0500 is only half an hour after they open, I'm pretty sure you'd make your flight if you were in line by then.

No idea if the Global Entry queue is open yet, it was closed when I went thru in Feb