In DEL the AI transfer desks in the centre of the arrivals level are either super crowded or closed. So the modus operandi is to turn right after getting out of customs and walking to the domestic side of arrivals. Over there you have a way to get upstairs (to the departures level) after convincing a CISF jawan that you are eligible. (T-4h used to be the magic time). If they let you up you get to a glass box where you have yet another CISF barrier to pass (sometimes they make you wait in the glass walled holding pen) and then you waltz over to the AI domestic checkin desks. Note that the *G /business counters are a bit hidden from view.