Generally speaking HHonors will announce the fall quarter promo soon (before the beginning of the next quarter). It will show up on the usual suspects of various travel blogs and FT. Hilton, unlike some chains, seems to be in the habit of having a promo every quarter. (There hasn't been any rumblings of this changing, which of course does not mean it couldn't change, past performance future results disclaimer blah blah blah.)

Slightly before then (say around the middle of the month preceding the end of the quarter), worried FTers will start posting threads in the HHonors forum consisting of (loosely paraphrased) "when's the next promo being announced?!?!?!?"

Congratulations, this time you get to be the first poster to do this.