I think you need not worry on this issue and go in this train itself, otherwise if you change the train then you have to reach one night before and this will incur dormitory or hotel charges which will then be equal to the cost of Sleeper Class in Duronto Express. According to the Arr/Dep History it is known that this train reaches atleast 15-20 mins early than the scheduled time,so I think you need not worry, just go ahead and you will also have ample time to change your train.