Mass...I love Centennial. Regarding primary, I take it from the perspective of where I'm at with fermentation. I like to be nearly down to FG but not quite. It's just something I've found to help clear. For normal alcohol beers like this one, I've found a week is fairly common. Again, this is my first jump into all grain. So, that may change things a bit, but extract brewing I've gotten in that rhythm.