I'm sure this is documented somewhere, perhaps just a pointer is required. I have purchased a flight on a BMI ticket but UA metal to LHR from LAX via ORD. The ORD-LHR leg is the new C As a 1K I have a few SWU's up my sleeve plus miles. What's the best way to score upgrades? I've heard SWU on day of departure is the only option. Is that done at check in upon request with a UA agent or at the Kiosk or do I need to request ahead of time? Not an option through .bomb...

Cheers