The shape of a good story in usually implied in all of its parts, including the beginning.
It’s always a good sign when the reader is able to guess at that ultimate shape from reading the first two or three chapters, rather like a paleontologist inferring the shape of a T-Rex from a couple of bones. Conversely, if the animal as ultimately reconstructed turns out to be wildly different from the one suggested by that first handful of bones, an acute observer may well conclude that something went wrong — either in the final assembly, or in the selection of parts.
Most readers are more acute observers than you might think. And writing a story whose front end promises something that the rest of the story doesn’t deliver is a prime route to reader disgruntlement.
Dr. Doyle's Blog 