I'm making a yeasted sourdough starter per the directions in my bread-machine book, but with rye flour instead of whole wheat. It's supposed to sit for 2-5 days, but it doubled almost immediately and is doubling again in my largest bowl! I can stir it down to keep it from overflowing, as it did the first time, but is it OK if I let it stand for another 6 days, when I plan to make the bread?
As another commenter asked, are you using store bought yeast or a sourdough starter? If you're using a starter, you can store it in the fridge, covered and then take it out a day or two in advance and give it feeds every 12 hours or less depending on its doubling speed. If its store bought yeast I wouldn't take the chance and would throw it out.
It's store-bought yeast - I'm making a yeasted starter for my bread machine, and the yeast itself is OK (I use it regularly, including just the day before). But the "doubling" problem resolved itself after I stirred down the mixture once or twice.