On day 4, we started getting fizzy noises when stirring the dandelion root mixture, so I stuck it in the fridge until we're ready to use it. We're waiting on sugar, as we don't actually have any in the house, and honey apparently doesn't work well for this application, given its antibacterial properties.
I think we're starting with just a liter. I have a hard time believing this will actually work, both in general and after the refrigeration, though everything has gone swimmingly so far. Since we're using an extract for flavoring, making a tiny batch shouldn't be much of a pain.