Delhi
Indira Gandhi International (DEL) is the busier end of this pair, and the one detail worth checking before you leave home is which terminal your flight uses: Delhi splits its domestic departures across more than one terminal, and they are a shuttle ride apart rather than a walk. That matters more here than on a short hop, because the southbound schedule clusters into an early-morning bank and an evening bank — miss the 06:00–10:00 wave and the next genuinely convenient option can sit several hours later, in the 17:00–21:00 block. December and January add a second complication at this end specifically: north Indian winter fog can delay the early-morning departures that this route depends on, so on a fog-risk morning a mid-morning DEL slot is often the safer booking even at a slightly higher fare.