Buddy, In my opinion you should avoid 12903. reason being in month of Dec ( Specially after 15 Dec, Flights gets delayed a lot). Also Traffic is nightmare in Delhi , trust me it will be big risk. If you are thinking of taking metro , please keep in mind Metros are jam packed in the evening time so it will be big headache if you are travelling with lot of Luggage
Suggestion : 1) My suggestion if possible go for a flight which is landing before 1400 hours in Delhi if you want to catch 12903.
2)...
more... Else go for some night Train like Jabalpur Attari express etc. Or make an overnight stay in Delhi. You can easily get very nice hotels in less 1.5k in Delhi Airport ( Try Lemon Tree etc, they give 8 hours stay package)
Cheers!!