So, I have two pure pitch packs of whitelabs yeast, and I am looking around at brewersfriends starter calculator to get a sense of what starter I need to make for my 2 coming brews. The first I'm about to use has an expiring date of april 24, the other may 6. I've been googling around and the info is a bit conflicting. Do I backtrack 4 or 6 months to get the manufacture date to calculate the starters on?