The development of the mesophase has been studied by either fast scanning calorimetry or conventional DSC in a series of random propylene-co-1-octene copolymers. The results show that the mesophase formation rate can be easily tailored in a very wide range of magnitudes, covering almost 4 orders. That decrease is similar to that found previously in propylene-co-1-pentene copolymers at the same wt % of counits. On the contrary, the pertinent unit for the melting point depression (and for the crystallization temperatures) is found to be the mol % comonomer content. Consequently, the "kinetic" parameters in the ordering of iPP copolymers can be tailored somewhat independently of the transition temperatures just by changing the size of the comonomeric units. Additional X-ray diffraction experiments, employing either conventional or synchrotron radiation, were also carried out on these 1-octene copolymers in order to determine the precise nature of the different transitions.