Cover the bowl and leave the dough to ferment at room temperature.
During the first 90 minutes, perform three sets of stretch-and-folds at 30-minute intervals. Wet or lightly oil your hands, lift one side of the dough, and fold it over the center. Turn the bowl and repeat from the remaining sides.
As the folds continue, the dough should gain strength and begin holding its shape more confidently.
After the final fold, leave it undisturbed until it becomes lighter, smoother, and visibly aerated. Small bubbles may appear along the sides and beneath the surface.
Bulk fermentation usually takes around 3–5 hours in total, depending on the temperature of the dough and the strength of the starter.
Do not wait for the dough to double. An increase of approximately 50–70%, together with visible bubbles and a soft, lively texture, is generally enough before refrigeration.