I also hit the berth immediately on boarding - before the train starts at around 22-10 itself; but be watchful for your luggage. Sleep hard when the train starts. There might be some disturbance at BNC for addl boarding, if any berths are vacant in you bay. Better to set alarm for getting down at PER at around 03-50.
This train normally trails Kerala exp from JTJ upto KPD. Sometimes, this mail is detained till in JTJ till Kerala exp departure.