[TxMt] Setting the filename of a new file

I'm using TextMate to keep my daily log book - I have a 'Journal' template, language and snippets and it all works very nicely.

What I'd really like is that when I create a new file from the template, it immediately gets a filename based on the date - eg. 060418.txt - so I don't have to enter that manually when I go to save it.

The template creates the new file in the usual way, by copying some standard contents to $TM_NEW_FILE. I was hoping that I might then be able to call osascript and do something like

tell application "TextMate" to save the document of front window in "060418.txt"

but it doesn't seem to work.

Any suggestions most welcome!