In DEL, for international connections/transfers, you do not need to switch terminals. There is mainly only one terminal used for international flights, the swanky T3, which has been awarded, time and again, as one of the best airport terminals.

That said, try to see if you can interline your bag through to your final destination. If you can, then you can stay air-side (not sure if you have to go through immigration, but you have to go through transfer security).

If not:

1. After deplaning, try to walk over to immigration quickly. It is about a 15-20 min walk, depending on where they dock.

2. They have separate lines for F/J pax. However if it is relatively empty, sometimes they call the Y pax over. It may sound DYKWIA, but, if you are pressed for time, get in the F/J line, and assert that you are a premium pax, and have a international connection. People are generally understanding. The premium counters are easy to miss: they are to your left, as soon as you alight from the escalators.

3. Claim your bag, 'exit' the bag claim area, and follow signs for international departures. Pretty easy to find since you will be arriving/departing from the same terminal

4. After checking-in, again, for immigration and security, there are separate queues for F/J pax, which usually move quickly. Keep an eye out for 'em, as they are usually well enforced.

5. KLM uses ITC Green Lounge for it's C pax, next to Plaza Premium and AI lounges, in the second level, above the duty free shops.

Hope that helps!

PS: Look at the India forum/India based airlines. You'll get more info there.