I wouldn't worry too much; as Ham says, you're going to knock it back later anyway. IME floured cloths will lead to even more stickage, though they can work well for the final proof. Sourdough doughs are usually fairly wet, so will be sticky until you've got gluten formation going. I personally like Dan Lepard's approach, which is to use a high-hydration dough and give it minimal working at ever-longer intervals; from memory it's eight stretch-and-fold moves on an oiled board at 15min, 30min, 1h, 2h, and 4h before the final shape and prove. Wet doughs form gluten without working over time, so over the period the dough will become less sticky; they're also less susceptible to over-proofing, so the timings can be much more flexible. I tend to make the sponge the night before, add the remaining flour and the salt in the morning, then work during the course of the day; depending on how much time I've got, the bread can go in the oven any time from lunch onwards, though it's usually late afternoon/early evening.