The results of 3D multi-fluid simulations discussing the observed early ingress, absorption in MgII resonance lines during the transit of WASP-12b are presented. The model is based on the multi-fluid approach which deals with H, He, Mg species and related ions. The model includes the basic hydrogen chemistry and provides the self-consistent description of the nearby planetary environment and a bow-shock creation in front of the highly irradiated exoplanet WASP-12b. It also describes the mass loss process in a self-consistent manner. The dynamics of MgII ions and transit light curves are estimated. The results with a set of stellar wind parameters and XUV flux values under a realistic Sun-like star condition showed that the planetary atmospheric mass loss rate is proportional to the stellar radiation energy input. The simulated transit light curves demonstrate early ingress as it was observed in the near ultraviolet measurements.