Time sensitive: Adding interview duration to SurveyCTO


I have a brief and urgent question. Can anyone advice me on how I can add interview duration into an existing questionnaire? I know this feature is very important for quality control and I have no clue how to add it.

Any advice will be very much appreciated.

SurveyCTO is closed-source platform that built on an earlier version of the ODK tools. If you have questions about it, see https://www.surveycto.com/support.