In the film Astrid speaks with a Stockholm-accent, while in real life she spoke with a noticeable Småland-accent.
After the dance scene at the beginning of the movie it is mentioned that Astrid is 16 years old, which would set the story into 1923/4. The song that the band is playing is "Yes Sir, That's My Baby", first released b Gene Austin in 1925.
The movie is mostly set in the 1920's. In a scene from Stockholm the bridge "Strömbron" is clearly visible, that bridge wasn't constructed until 1946.