Thanks to some contests I've come across recently, I've started re-evaluating my opening scenes. Having cut my teeth on the work of Nora Roberts, an expert at the slow build, I don't necessarily need instantaneous impact in paragraph 1, Chapter 1 for me to buy a book. There doesn't have to be an explosion on the first line, actual or metaphorical, for me to want to continue reading. But we hear over and over again how critical it is to hook a reader immediately; in fact, that's probably one of the first things we're taught as writers. Start "en media res" - in the middle of things.
I frequently rely on voice as my initial "hook," because truthfully, I often like to start just a few moments before the inciting event, to allow the reader to invest in the character a bit first. Some books I start at the point of impact. But lately I see more and more how critical the beginning is - a catchy voice is great, but if there's not a hook, often in the first line, an editor or agent may just give up and move on. And that says nothing about readers.
As a writer - and reader - how long do you give a story before you take it up to the checkout counter (physical or virtual) or put it back on the shelf? And in your own stories, do you hit the ground running or acquaint the reader with the character first? Probably the sweet spot is managing to do a bit of both, but I'm curious if you have to know a little about a character before you care he's about to be eaten by a huge winged dinosaur. ;)