How do i start a past perfect sentence with "not until"

My teacher gave us this question

After we had done our work , we watched a film. Or in another phrasing We didn't watch a film until we had done our work

And told us to try and solve it and that he won't tell anyone the answer or ask for it he just wants us to try.

So after 2 hours of searching i still don't know if my answer is right or not so i would really appreciate if someone can tell me the answer.

My answer is "Not until we had done our work , did we Started watching a film"

Submitted November 03, 2021 at 06:49AM by Background_Ad_7334 https://ift.tt/3CCDPHj