file system checks

We deliver files to a ftp server for pickup by our customers. we want to verify that the file is deliverd at a cetain time. I have setup a file system check to verify the file is there however when the next day rolls around and the file is overwritten I need a way to verify that the modified date is new. I see that the modified date is collected but it has no threshold or alert ability. I'm needing the file check to alert out if they date is not the current date. It would also be nice to have the capability to have it check only durning a certain time frame. I think i could solve that problem with the scheduled downtime capabilites in adventnet.