Just went through this for the first time as I get free seats as Gold. Flying with my mother on Monday on separate tickets and she's in a special and no status so at exactly T-48 checked her in and all seats had been assigned prior to OLCI, the only 2 seats together happened to be twins so happy to have snagged them, but point being that even at T-48 seat selection will be limited. Upper deck A380 definitely nice