SQL Server stores a create date and a change date for each object in the sys.objects system view.
Unfortunately while tables, views and even constraints are objects, indexes are not. Or at least they aren’t stored in the sys.objects system view. And the sys.indexes system view doesn’t have any dates associated with it. So how do we get the create/update date on an index? Well, short answer is you don’t. Long answer is that in some cases you can get some information.
These aren’t ideal answers, but they can be better than nothing.