We just installed a new pool (vinyl) here in Michigan and the installer did not turn on our SWG for the first week to 10 days. When I read the literature on the unit (Intellichlor IC40) I remember reading something about plaster pools needing to cure for the first 30 days (didn't concern me), but also that when a new pool is first filled the water often has impurities in it that can cause damage to the generator's cell - so they recommended not running it at first.