if you're using a stir plate then it'll probably be done in 24 hours. Otherwise it'll probably finish up between 48-36 hours. Are you anxious to brew or something?
This is a lager starter and I'm planning on decanting the 2 qts of liquid, so I want to make sure the yeast is done before I put it in the frig to chill.
I shook it a couple hours ago and it foamed about 1.5 inches. I shookt it a few minutes ago and no foam. I guess it's done.