Orange Juice, the matronly orangutan, floated to the lifeboat on a raft of bananas, and it was the morning after the shipwreck. Pi spent a terrifying night aboard the raft with the tiger and hyena, and the following morning, Orange Juice floated to them. Pi describes her arrival as joyous news:
"She came floating on an island of banans in a halo of light, as lovely as the Virgin Mary. The rising sun was behind her. Her flaming hair looked stunning."
This description is right at the beginning of chapter 42, and the "rising sun" describes the morning, which is the morning after the shipwreck. So, she comes to them pretty quickly. Her arrival is so wonderful to Pi, because she is a friendly, loving animal with whom he had had many positive experiences. In his desparate situation, any friendly faces were a welcome sight. I hope that helps a bit; good luck!
Orange Juice makes her first appearance in chapter 42, the first morning on the lifeboat. Pi has just spent an terrified and sad night devoid of human companionship on the boat with the hyena and the injured zebra. The orangutan makes for a very welcome sight to Pi because she is a 'good animal' and more familiar to him then the other two.