Ok I can't help myself so let's get ahead of that then:
When's the next DSC Promo? = It hasn't been announced yet but expected shortly.
Will I earn DSC on Alliance? = Yes all QantasLink services including operated by Alliance, National Jet Systems, Network Aviation, Eastern Australia Airlines and Sunstate Airlines are eligible.
Where did all the sale fares go? = Sales and DSC/DP promos don't typically occur at the same time.
Has anyone's DSC posted yet? = DSC's typically take a few days after the flight to post however on the first flight of your DSC promos this can take longer up to several weeks.
Does a QF flight number on EK metal count? = Nope (nor do any other QF flights not operated by Qantas or QantasLink airlines see list above).
Don't talk about Fight Club. = Don't know what you're on about

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Come on! I just booked J flights to XYZ :-( = If booked within 24 hours and departing from AU then you might be eligible for free cancellation otherwise too bad, you're subject to full cancellation if you wish to cancel and rebook (a change doesn't count).
Will I earn DSC for flights I booked 3 months ago? = Nope.
Does this mean there won't be another DSC promo in [month]? = Qantas decide and announce the DSC promos and never give any early indication, there is some consistent patterns with one at the start of most years but as with most things in life, nothing is guaranteed.
I want to add some more based on this thread:
Non 081 QF ticket stock? = DSC still applies if QF flight number and operated.
Award tickets with Points Club? = Yes eligible for DSC if booked during the time frame.
I have a flight credit is this eligible? = No a new PNR needs to be created and as flight credits are an existing PNR they are not eligible.
Do Qantas flight operated by Finnair count? = Yes as they are a wet lease they do count for this promo.
Do Jetstar flight count? = Nope.
Can I book via a travel agent or Amex? = Yes, they count.