What did you do that day? (two months ago in the middle of the process) [migrated]

1: I started painting a picture ten days ago. I haven't finished it yet. Everyday I've been painting my picture for half an hour.

2: I started painting a picture three months ago. I finished it one month ago. It took me two months to finish it. Everyday over the period of two months I painted my picture for half an hour.

If somebody asks me: What did you do yesterday/that day (in the middle)? What should I answer?

1: A: What were you doing yesterday?

You: “I was painting.

2: “What were you doing between September and October?”

You: “I was painting a picture.”

1a: A: What did you do yesterday?

You: “I painted.”

2a: “What did you do between September and October?”

You: “I was painting a picture.” (The continuous is used as the action was not complete at the time referred to.)

2b: “What did you do in November?”

You: “I finished painting a picture.”

You will note that answers are usually (but not always) given in the same verb form as the question.