It arrives at 1315 leaves to VPM at 1400 arrives at 1500 according to you 6hrs SM then 2100 reaches PDY at 2200 and can leave at 2300. This is a condition that it never gets late even by an hour. So departing at 1930 is impossible. If they LHB rake then too it needs SM at one way distance is 2350km and return trip is 4700km which is more then 4000km. They can advance the dep to Morning 650 to arrive at 2100 in return.