We develop a dynamical approach to study the Casimir-Polder force between an initially bare molecule and a magnetodielectric body at finite temperature, valid for arbitrary magnetodielectric properties and also in the presence of chiral effects. Switching on the interaction between the molecule and the field at a particular time, we study the resulting temporal evolution of the Casimir-Polder interaction. The dynamical self-dressing of the molecule and its population-induced dynamics are accounted for and discussed. In particular, we find that the Casimir-Polder force between a molecule and a surface oscillates in time with a frequency related to the molecular transition frequency. We verify that the dynamical force converges to the static ...