When do you want to make the reservation?

Question

-I want to make a reservation for Collins.

-How many nights?

-Two nights.

-For when?

This is a dialogue between the staff of the hotel and the client. But, I haven't heard before the expression "for when?". Is this correct?

Answer 1

Yes, it's common usage. Really the person should say: For when would you like to book the room? or For what dates would you like to reserve the room?. But in real life: For when? is very normal.

Answer 2

Yes, although it is rather informal since it has no verb, making it a fragment rather than a complete sentence.