After 15min take the dough on clean platform, knead it using stretch & fold method, use little oil if the dough gets sticky, you can also wet your hands while kneading (make sure you don't wet your hands too much or else the dough will become watery). Knead for around 10-12min & then transfer the dough into a well oiled bowl, the dough should reach the stage where if you like your finger into it, it should bounce back.