ATJ,
I didn't remember the WT typology on Job at all. I suppose Gilead instructors are drawing on very old WT literature inasmuch as it contents have not been overruled by some "new light" since. This reminded me of one episode when I was a (very young) pioneer. I had conducted a "Bible Study" with a rather smart guy for many months but he never came to meetings. Back then we were instructed not to pursue Bible studies too long if the student didn't "progress" towards becoming a JW (and the first step was meeting attendance). So I told him I would have to stop if he didn't come at least once. Well, the first time he came there was a public talk on some old outline I had never seen or heard, about the book of Judges -- and it was all fancy typology (one detail I remember is that the lion Samson killed typified... Protestantism!). I was terribly embarrassed about this guy hearing that kind of stuff... I discussed with him next time (in the spirit of "don't bother too much about that"). Well, this guy and his family became JWs after I moved. Years after I met him incidentally and he gave me the perfect shun. :(
I am not convinced that Job 1:4 refers to birthdays though (although it can't be ruled out): "(on) his day" (yomo) alone could have this meaning, but the full expression 'ish yomo corresponds to a very frequent distributive structure in Biblical Hebrew which may mean simply "in turn".