Looking for advice from Edmonton (YEG) travellers on US preclearence cut off times.

Trying to catch a Thursday United 3:35pm flight to ORD. I have a meeting in the domestic departures terminal post-security section until 2:30. I'll already have my boarding pass and no checked luggage. I assume I will have to leave security and go back out.

Can I get through US preclearance at 2:45 in time for the flight (both from a immigration clearance process and will they even allow me through so close to the flight time)?

If it matters, I'm a U.S. citizen and don't have Global Entry.

Thanks in advance!