As a native English speaker, I would never understand this English phrase. Context might help, but I doubt it. I would ask the speaker to clarify. I don't know exactly what the German phrase means and, with this English translation, I still don't know.
Without context, I took it to mean "at our choice of time (for starting or doing something). "At our time" makes no sense to me. Could it mean "In our good time"? In! "In our day"? In! "In this day and age"? In, again! When do we use "at" with time? "At the right time." "At a time of your choosing". I can't think of any context for "At our time". Use any possessive noun or pronoun and still it makes no sense to me. I have many guesses but no certainty as to what the German sentence meant to convey. Perhaps a subsequent example will clarify the meaning of "zu --- Zeit" and then we can come up with a better way to say this in English.
Perhaps a spaceship, carrying the holy potato, left another galaxy where they they are always on daylight savings time. It is due to arrive here three million years after the departure, but it is unclear whether that's eleven AM their time, or ours. "And at our time?" is an awkward way to ask the question, but you can imagine that everyone is tired, and they may even miss lunch.
It's hard to imagine making use of a phrase without knowing what it means in what context.
Maybe 1 group of time travellers are trying to organise a dinner date with another group of time travellers from a different time. Where they have already chosen the restaurant, but then one group responds "and at our time?" to clear up which time line they will be meeting.
Still 'in' would work better, but this is the best fit I can do... anyone else?