I am brewing a Bavarian Hefeweisen. Starting gravity last night was 1.080 and I pitched the yeast WPL380 at 72 degrees. It has been approximately 18 hours and I have not started to see any activity in the blow-off and no krausen has started to form. Should I be worried? The wort is at 72 degrees right now. I did not use a starter for the yeast. How long should it take to become active?