I am working in Forkish book (Flour Salt Water Yeast), the recipe "White Bread With Poolish" on page 98. He prescribes a 12-14 hour unrefrigerated fermentation for the poolish. I read in another book that this kind of poolish fermentation could be lengthened to 24-48 hours to move toward a bread flavor somewhat like sourdough without all the work of developing sourdough