We study the initial nucleation dynamics of poly (3-hexylthiophene) (P3HT) in solution, with particular regard to the effect of rigid backbone length on the ordering dynamics. We carried out Langevin dynamics simulation, and found that the initial nucleation processes of P3HT in solution begin with the ring ordering, followed by the main chain ordering. In the meantime, ordering of side chains was slow and induced by the packing of main chains. This basic ordering mechanism is common regardless of chain length of P3HT in this study, although the longer chain systems showed slower growth than the shorter chain systems. Our simulation results demonstrated the unique and universal ordering features of comb-like polymers with flexible side chains and rigid main chains in the initial crystallization processes.