What follows is all from recollection, and I don't have either my Windows 7 machine nor JAWS in front of me.
I presume you are already using the "Details" view in Windows Explorer to view the files contained in your various folders. If not, you need to set the view to Details view and I can't for the life of me remember how to do that in JAWS, but I believe it's via the View menu if memory serves.
When you are in Detail View at some point when you're tabbing around with JAWS you will land on the "Name split button." If you immediately use your right arrow you should then be on the Date split button. You don't want to drop down the "drop downable" part of the split button and I think that just hitting space once you land on it will make Date become the primary sort for your file list. When first activated the Date sort sequence is descending, meaning newest file at the top to oldest at the bottom, an additional press changes the order to ascending, oldest file first to newest file at the bottom.
I'm sorry I can't be more definitive about this but at least you have something to try. Please report back as to whether my description was enough to allow you to get the result you're seeking.