Include the dates when the conference was held.
The template below shows how references are constructed.
Author(s) OR Organisation. … (year of publication) …… Title of conference … dates conference was held. … Place published: Publisher/Organisation
The Royal College of Nursing (2019). RCN 2019 research conference, Sheffield, England 3-5 September, 2019. London: Royal College of Nursing.
Note: If the conference proceedings are published, the date of publication may be different to the conference date – both dates need to be included.