I was taught to always drain immediately after fueling. Shouldn't I instead drain as the very first thing before the aircraft is moved at all because movement and pouring fuel into the tanks must stir-up any water in the tanks ?
After refueling with avgas, a short settling period is highly recommended.
With turbine aircraft this is not especially necessary, however with these aircraft, the 'penny-in-the pail' technique, prior to refueling is many times practiced by older biz-jet crews.
Also highly recommended.