Reading the SDFC and standby threads but very confused...

my question:
Planning to book a mid-evening flight as an award ticket for two passengers: me (GLD 1MM) and non elite companion
Flying from outstation to more major AA destination
Likely to want to fly earlier in the day

Will AA let us standby, and if so would I have to pay for myself or companion?

New info suggests this doesn’t depend on E inventory. EF shows quite a bit of E inventory that day but this is several weeks out and that may change.

And a bonus question: what about the possibility of standing by the day before, more than 24hrs out? Does that ever happen?