@alan33921 The code in my original answer must be on the dataset’s onBeforeSave() function, and if you’re using wix-data to inset then just before the insert call.
Yes it does this before even saving the form to the database, and yes it’ll calculate it very fast since it’s a simple calculation as you can see, and when sorting on the other page, the sort will use the field that we used to save the seconds, less seconds (shorter periods) will rank higher.
If you need anything just reply back.