i think this question is better suited for the 'airlines of india' forum....

when in december are you traveling????the biggest problem in delhi in december & january is the fog....it normally starts to set in around mid december & carries on till the end of january or beginning of february....lots of flights get canceled or delayed....

since you are on a single itinerary, in case your flight is delayed, jet will probably rebook you on the next available flight without any extra charge....