From killing the Celestial Dragons to leaving the Shapodi Archipelago, Su Xiao spent less than five minutes in total; this was the result of ten days of preparation.
From beginning to end, Su Xiao never planned to show up inside the Slave Auction House; three shots to kill the targets, then a rapid departure from the Shapodi Archipelago. The plan looked simple, but in reality Su Xiao had been working on it for a long time.
First, Su Xiao had to wait for the Straw Hat Pirates to make landfall; second, he had to make sure Kaimi was kidnapped and sent to the Slave Auction House.
According to Su Xiao's conjecture, the Celestial Dragons appearing at the Slave Auction House was not something guaranteed. Those three Celestial Dragons most likely heard that there was a merfolk for sale, and since they just happened to be on the Shapodi Archipelago, they went to the auction house.
