The moment Aang's spirit arrived on the turtle, Wan was aware of it. The tug on his soul was undeniable and he dropped what he was doing (literally. he'd apologize to Zuko about the broken plates in the kitchen later) to fly out the door and head on over. It took him several minutes to get there, even flying as fast as he safely could, but it was mostly during the time Aang was pushing the nausea down.

When he landed, he was all smiles and there was no hesitation as he ran over and pulled his future life into a hug, "Aang!"