Jack was woken up by a knock on the door. It was Celine, reminding him that it was almost time for them to depart. Although Celine had previously had no intention of coming back to the prince mansion after the swimming pool incidence, when she remembered that she was now competing with Wendy, she decided to take this opportunity to come upstairs and wake him up.
But of course, the moment that Jack woke up, she had already rushed back downstairs, not waiting to be reminded of what had happened back then.
Jack got out of the bed and headed downstairs after he was done with changing his clothes. He was fully prepared. Since they were going to hang out, there was nothing that he had to prepare other than dress properly and have enough money to spend.