Although Nick doesn’t realize it at first, Gatsby arranges for him to have lunch with Jordan as part of his plan to get close to Daisy. More specifically, Gatsby wants to arrange it so that Daisy will come to West Egg, where she can be reunited with Gatsby and witness his wealth firsthand. Having Daisy come to West Egg has the advantage of isolating her from Tom, and also makes it possible for Gatsby to stage an apparently accidental encounter with her. In order for these events to happen, Gatsby needs Nick to invite Daisy over under the pretense of having tea. Instead of asking Nick to do this himself, Gatsby employs Jordan to convince Nick. The meeting between Nick and Jordan in Chapter 4 is part of a longer-term plan that Gatsby initiated before Daisy moved to East Egg. According to Jordan, Gatsby has kept tabs on Daisy for years and followed her when she and Tom moved from Chicago to the east coast.