code: def is_too_early_to_signup(self, now=None):
          
          if now is None:
              now = datetime.datetime.now()
  
          activity_date = (datetime.datetime.combine(self.block.date, datetime.time(0, 0, 0)))
          # Presign activities can only be signed up for 2 days in advance.
          presign_period = datetime.timedelta(days=2)
  
          return (now < (activity_date - presign_period))
docs: Return whether it is too early to sign up for the activity if it is a presign (48 hour
          logic is here).