Don't worry all the counters will be available for tatkal.. How many are there.. If they will do it fast, then your number may come in at least 30 mins.. But it may be fast as the main rush would be for Hjp-Mfp bound trains and once the waiting will be there in those trains people will leave the counter without taking a ticket. Also try for 15484, last time I was there the last train for fill was Mahananda..