Selection of a suitable time step size is essential for accurate CFD-DEM simulations involving non-Newtonian fluids. This study explores the effect of power-law parameters, the consistency index (K) and the flow behavior index (n), on time step sensitivity during fluid-driven fracture initiation in granular media. The results show that the power-law parameters have a strong effect on fracturing behavior. Less viscous fluids create infiltration-dominated linear fractures with lower peak pressures, while more viscous fluids produce wider fractures dominated by grain displacement and higher peak pressures. The analysis of injection pressures at various time step sizes indicates that CFD time step sensitivity is influenced more by the flow behavior index rather than the consistency index. Lower flow behavior indices ( \(n = \) 0.1 and 0.2) demonstrate relatively accurate results at a higher time step ( \(\Delta t = 10^{-4}\) s). In contrast, when n increases to 0.3, the errors become more significant, which in turn requires a reduction in the time step to \(\Delta t = 10^{-5}\) s.