I think it’s the second because you’re asking about an action already finished.

What time did you finish your work? - Great. A simple past, absolutely right for a point in time as you need here. What time have you finished your work? - Nope, sorry. You could ask By what time have you finished your work? - this means as in each day, something repeated, ongoing. But otherwise, finishing is a point in time, and needs a simple past. What time do you finish work? - again, as if repeated, daily, or similar.

I would say the second, "what time did you finish your work?" You could also say: "When did you finish your work?" And it would still be in reference to the time.

Usually, i finished my work at 6 or 7pm.

The latter one , I guess.