Originally Posted by
canadiancow
If it's confirmed at check-in, it's not standby, it's a same-day change.
Standby is, as far as I know, always done at the gate.
I realize that the passenger doesn't have status, but you can have standby confirmed at the check in counter if you are Super Elite - at least going LGA>YYZ...they just confirm it with the Concierge and you are good to go. I have done this on more than one occasion.
Good luck!