Hi Jenny
No problem, you just need to create a new field in Admin that is either a "Date" or "DateTime" field and add to your flow the below change data value step. My example is a "DateTime" field. The token will stamp the exact date and time that the action happened for each lead record it happens to.
If you don't have this in your flow already, if there is something unique that happened in the webform flow (e.g. alert was sent or added to a list), you could use a smartlist to look to see how many people had that action happen to them in a specific date range. This could take a while if you wanted to know daily though, but if you need to report on the data, this is an option. Example below if say an alert was sent:
Hope this helps
Daniel