So I got my stir plates working. Time to use them. My yeast, unfortunately, isn't the freshest. The WY2206 is dated 4-24-12. The WY2278 is dated 2-01-12. (The yeast calculator indicates only 13% yeast cell viability in the WY2278!) Anyway, how long will a 1.5L starter take to ferment out before I step it up?