If at first you don't succeed...
I've been feeding my starter every 12 hours since Thursday evening. It isn't too lively: I'm getting some growth and bubbles, but nothing close to doubling in size.
I went ahead and fed it again this evening. I put it in the oven with just the light bulb on, which keeps it around 80 degrees. We'll see if a slightly warmer environment stimulates it enough that I can bake with it tomorrow. If not, I may cheat and make a sourdough that is spiked with half a teaspoon of yeast, since it *smells* like sourdough. I'd like to get a chance to taste it.
I went ahead and made a poolish tonight too, so at the very least I could make a decent loaf of French bread tomorrow.