Your question is very general. To measure the effect of any intervention (before and after), the time interval is different based on the intervention topic.For example, for educational intervention, at least two months.

Thank you for taking the time answer this Ehsan. I understand it is down to the individual interventions. My study is a non intervention, exploratory study with healthcare professional who look after patients with a short term urinary catheter. After doing an audit of current practice, I chose a 2 week follow up period. I just wondered if anyone knew of a similar study that I could use as a reference.

Best wishes

Rashmi