filter for first sheet in transform file parameter (connecting to excel files in a folder)

I'm attempting to connect to a folder of excel files in Power Query.  I want it to pull the first sheet regardless of the sheet name. The query to load the data references the "Transform File . . " parameter as opposed to any specific sheet. I've seen demos where you can replace absolute sheet names with {0}, {1}, etc  but I am not sure how that would work in this scenario:

The "Sheettest" is the first sheet in this example.