First and during reload, create a calendar. Connect the data in your data model to the field that conatins dates. Lets's call that field CalDate.
Then make a list box with an expression like (shows today and previous six (6) days):
=IF(CalDate > Floor(Today())-7, CalDate)
Since the listbox will show a maximum of 7 dayes, there is no need to turn it into a dropdown object as this is usually too much layout work. If you really want to create a dropdown, you'll have to assemble one using buttons and a listbox that is conditionally shown.