"Πότε είχες έρθει;"
Translation:When had you come?
When would one use this tense? Many of these sentences sound odd in English (Is there any context that When had you come? could work in?).
In greek it would be used in that context: Εκείνη τη μέρα, πότε είχες έρθει στο σπίτι, το πρωί ή το βράδυ;=That day, when had you come at home, in the morning or at night?
It's also correct. But, έχεις έρθει gives the impression that the action happened a lot of time ago, than ήρθες. Generally, past perfect is used the same way as in english, though. Ie an action that was complete before another in the past.
In that situation I would use the simple past in English "on that night, when did you come home?"
This tense is called υπερσυντέλικος in Greek. It is exactly the same as in English, I think. An action that done and finished some time ago. Not necessarily a long time ago, it can be even today. BUT finished.
ερθει can be used in the present tense or in the future, so it is not correct. arrived can mean ήρθε