When and where you execute the microflow to generate and store the URL is up to you.
Question is; When is the data known to generate the deeplink?
When certain data is entered, retrieved, set? add the microflow you created as sub-microflow in that process.
You can get the Deeplink module to pass a parameter to a microflow. This can be an ID or any other token you create that you can use to retrieve the entity and show a page.
You can also use the built in URL functionality on a page. The ID you need for the link is the ID of the entity in the page parameter. You can get his using the Community Commons getGUID Java action.
Hope this helps.