In this work, the formation of flow-induced precursors (FIPs) during and immediately after applying a shear flow in isotactic polypropylene (iPP) melt is studied at high spatial resolution and high time resolution with a high-speed polarized optical microscope (HSPOM) and simultaneous small/wide-angle X-ray scatterings (SAXS/WAXS). A number of studies have reported the formation of FIPs in the early stage of flow-induced crystallization. However, reports on direct observations of the formation of precursors during shearing are scarce. We find that FIPs are observed using HSPOM after a certain incubation time during shearing. After cessation of flow, some FIPs dissolve gradually and others transfer to crystals. This suggests a competition between chain relaxation and crystallization. In SAXS measurements, the formation of FIPs during shearing is indicated by weak equatorial streaks normal to the flow direction after a specific incubation time. The intensity integrated from 2D SAXS images shows a sudden decrease upon stopping the shear flow before it increases again during isothermal crystallization, similar to the results in rheo-optical measurements. WAXS measurements capture extremely low signals of crystallinity in the primary stage of the formation of FIPs, which is indicative of the very small magnitude of crystals in FIPs. Three crystalline components (alpha, beta, and gamma form) separated by Lorentzian fittings emerge in the late stage of shearing. The crystallinity of all components decreases immediately after shearing, and the fractions of the beta and gamma forms also decrease, which suggests a faster dissolution of the beta and gamma forms compared with that of the alpha form. Finally, residual precursors lead to the well-established "shish-kebab" morphology.