Listen to enough oompah music, chug enough beer and eat enough sausage to make such middling, everyday concerns like “Why is Oktoberfest in September?” disappear. Schroeder’s, one of the oldest restaurants in San Francisco, is here to help kick off the season with an all-out block party. Dance to tunes from the WonderBread 5, fill up on quintessential carbs and rock that lederhosen all night.