It's hard to figure out just exactly when
http://www.ilgradio.com/ilgradio.htm says we can get new files.
$ wget --spider -S http://www.ilgradio.com/ilgradio-datafiles/ILGBTEXT.ZIP
Last-Modified: Sun, 01 Feb 2004 21:02:08 GMT
So I should set my (wwwoffle) monitor program to fetch the file
Feb. 2, and every three months after that.

But one also reads the file is available starting 1 month after
creation. So maybe I should use Mar 2, ...

One could indeed just ask them, but one gets:
6. We don´t wish to receive e-mails with questions about any
publishing dates of ILGRadio. We will not answer to these mails.

Maybe they don't see that all we are asking is for them to use a
little clearer English on their web page; we are not voicing policy opinions.