Cover and allow to prove in a warm place for 3-4 hours (I put my banneton into a large plastic bag which I reuse again & again, but you can get special elasticated, washable banneton covers)
20 minutes prior putting the loaf in to bake, preheat the oven to 240ºC/475ºF/Gas mark 9
Put an empty, shallow baking tin onto the bottom shelf of the oven
Fill a cup with water and leave on the side near the oven until you're ready to bake the loaf