In my experience, unless there is a really high demand expected for J seats (maybe a world cup regby comp or similar), QF will release J to D for waitlisted WP's. So make sure you are on the WL and keep watching.

Now I just wish AA were a bit more forthcoming with moving J to D for waitlisted QF WP's. I have an ORD-NRT waitlisted that is showing J7 D0 (AA use 7 as QF use 9 to mean 7 or more available), and the seat map shows 22 unallocated business class seats. It just seems that AA set D0 on the Monday flights, while making plenty of D available on mid week flights. I need the waitlist to clear to make it back for the BNE Christmas Drinkies .