FTP - Sender File Adapter - Exactly Once In Order

We are running SP10 on PI7.0

I have a file (FTP - content conversion) to idoc scenario and this works well apart from the communication channel picking up the files in the wrong order.

I have set to Exactly Once In Order, and the nuemrically file is being picked up in the correct order, however we wish to pick the file up by time and date stamp.

If I flag the Adapter Specific Message Attributes - and Source File Time Stamp, will this then process the files by timestamp instead of by File name?

How else can we get the files to process by time created?