When you first learn to bake sourdough, it is handy to use certain time guidelines to help understand how long to proof sourdough for, but you may find that your bread results are different every time.
As a very basic time frame, the very minimum that sourdough should ferment/proof for is 4 hours. 1. How much sourdough starter or leaven has been used in the dough 2. The temperature of the dough and its environment