There's no real standard as to exactly the distance from the butt. The measurements are usually taken from the tip of the rod and the distance from the reel to the first stripper can be played with a bit to accommodate the persons arm length that the rod is being built for. Short arms (kids) I move the stripper closer to the seat/grip. But normally the first stripper will end up right around 30-32" from the butt of the rod most times. If the stripper is falling right at the junction of the ferrule then move it forward up onto the female ferule. It is always better to put a guide directly on a ferrule rather than a inch or two behind one.

Steve