Board Thread:Questions and Answers/@comment-30150700-20161005162327/@comment-27384850-20161007153356

He didn't use the revival item, and he certainly didn't use two considering it was literally impossible for him to have gotten a second one. Kirito got the item on Christmas Eve 2023 (the floor was not open on Christmas Eve 2022) and the game was cleared in early November 2024, there is no possible way for a second one to have been obtained.

As for when he did it, we don't know. He could very well have, before the duel, set it to move anyone who died onto that floating platform, as everyone else was paralyzed by the system so only Kirito should have been able to die, and Asuna joined them because she was able to break paralysis.