When an electron-hole pair is optically excited in asemiconductor quantum dot the host crystal latticeneeds to adapt to the presence of the generated chargedistribution.Therefore the coupled exciton-phononsystem has to establish a new equilibrium, which isreached in the form of a quasiparticle called polaron.Especially, when the exciton is abruptly generated ona timescale faster than the typical lattice dynamics, thelattice displacement cannot follow adiabatically. Con-sequently, a rich dynamics on the picosecond timescaleof the coupled system is expected. In this study wecombine simulations and measurements of the ultra-fast, coherent, nonlinear optical response, obtained byfour-wave mixing spectroscopy, to resolve the forma-tion of this polaron. By detecting and investigatingthe phonon sidebands in the four-wave mixing spectrafor varying pulse delays and different temperatures wehave access to the influence of phonon emission and ab-sorption processes which finally result in the emissionof an acoustic wave packet out from the quantum dot