I have had a 1 litre starter that's been on a stirplate for a little over 48 hours now, and there are still absolutely no signs of activity. When the plate is off the surface is totally still, so I can't imagine there has been any gas production at all. The two smaller steps in the beginning of the week we're normal, and the slant I inoculated in transfer to this vessel had colonies overnight. How long is too long to see a starter take off, and should I just go buy a pack of dry if I'm gonna brew this weekend?