We've been having this discussion on the Crime Thru Time list. Some historical mystery authors prefer to unfold their book slowly, telling about the weather, describing the setting, revealing the players, and then several chapters in--boom! There's a body. It was my contention that, One: most of these authors have been published for quite a few years and this was accepted practice when they started publishing. Now, agents and editors seem to expect a little more movement, a snappier beginning to get to the story sooner. And Two: that there certainly isn't any one way to drop the body into the plot. Because I'm writing a "Medieval Noir", my pace is considerably faster than other medieval mysteries and the body shows up usually in the first chapter. I don't feel the need to let the reader get comfortable with the setting and characters first. Let them sweat it out with the protagonist. Let it unfold for the reader just as it unfolds for him. Let them absorb the setting as the story progresses.
What about you? When does your body show up? Are the demands of the publishing industry a factor for you in this? Or is it strictly writing style or even a product of the genre in which you write?