How should Serevent Evohaler (salmeterol xinafoate) be primed before first use or after a week without use?

Before first use or after a week without use, prime Serevent Evohaler (salmeterol xinafoate) by removing the mouthpiece cover, checking inside and outside for loose objects, shaking well to remove loose objects and mix the contents, and releasing two puffs into the air to check it works.