Stephen King fans wait with bated breath this week in anticipation of the first episode of “The Stand” mini-series, and as it turns out, there’s nothing to worry about. This nine-episode CBS All-Access adaptation opens with just under an hour of character introductions for three of its leads, and enough world-building to give the audience their bearings without overwhelming them. And while book purists might offer a few protests over some of the series’ character and plot changes (including one game-changing one in the episode’s closing minutes), each serves a purpose and elevates the material.