During the Final Selection Tanjiro mentions that it's currently the Taisho era, that would be somehwere between 30 July 1912 to 25 December 1926 so the start of the 20th century. So I think it fits pretty well with our world, the rural areas, e.g where Tanjiro lived, still having nothing in terms of "modern technology" but a bigger city and especially a city like Tokyo already having electricity, trams and trains and stuff like that.