You basically have 3 options:
1. Work with your scheduling group to put something together since most scheduling systems handle this already.
2. Since FTP is not a scripting language and has no tools for working with file names OR dates, if your scheduling group cannot help you then you can create the FTP commands via a program (or utility) and pass them into the FTP step.
3. You can go back to whoever the file is coming from and telling them you cannot handle dates in the file name and have them remove it.
You could transfer into a Unix System Services directory by using the FTP command MGET * to grab all files and figure out later which one is the one you need, but sooner or later the mount point will fill up and have to be cleaned out. And this still leaves you have to code up something to find the right file for the given date.