I know this doesn't answer your greater question about the timeline of companion upgrades, but even AS members can't get just themselves upgraded if they're on the same reservation with another passenger. It's both or nothing. And unfortunately, the AS upgrade processor is notoriously wonky when upgrading passengers on the same reservation. It often releases one seat at a time, which means if a couple traveling on the same reservation is sitting in spots number one and number two on the waitlist, they'll be skipped over in favor of the single passengers behind them in slots number three and four. To maximize your chance of an upgrade, it's prudent to spit reservations from your companion if possible.