Practical Travel Safety Issues - YYC (Calgary) preclearance times?

In mid July I have a 6 a.m. flight from YYC to ORD. How early should I get there? The hotel shuttle doesn't start until 4 a.m. Should I plan on a taxi? FWIW, I'm coming from Asia the night before, so I'm not very concerned about the early hours ;)

It generally depends on how many flights are heading to the USA around that time, but without Nexus I would plan to be at the airport roughly 2 hours before the flight is scheduled to depart. Sometimes this leaves me with a decent chunk of time and I grab a coffee and a bagel, other times I've just had enough time to board.

So, what exactly is the scene at 4:30 a.m.? Is the preclearance dept. even open? Or is there a huge line?

I don't have Nexus, so I'm going to be with the unwashed masses.

Last time I flew from YYC (June 2011) the soonest you were permitted to enter pre clearance was two hours, which is a total PITA, because the early morning flights produce a clog. It takes at least 60 minutes early in the morning to clear. I have cleared immigration and customs and security and arrived at the gate while it is boarding after entering the pre clearance hall at exactly T minus two hours.

However, YEG used to be the same way. But like YVR, the order of U.S. pre clearance and security has reversed. So the two hour thing is history. My guess is the same thing is coming to YYC if not already.

Also OP, there is an on airport hotel which is an easy walk to the trans border area. Stay there. If not, yes take a taxi that gets you there at at 3:45 am. Good luck.

Calgary preclearance opens at 0430. Summer travel season is about to start so mid July depending on the day you are traveling may be busy. Get there 2 hours early just to be safe.