Trust me, I wouldn't book a first or biz award seat on QF for dates I know I can't use: the likelihood of a different date becoming available later on is nearly non-existent. Also, in the past, when an award seat was taken from QF schedule, and then cancelled, it often didnt go back into award inventory, so booking a date just as a placeholder meant that the award seat would go back to the regular, non-award inventory (there's a recent discussion about this in the QF forum).
In the last two years, QF premium award seat release has become much more unpredictable. Depending on the route, premium seats can be released anywhere from 330 to 250+ days out. Often, only one premium seat is released per flight. Seats that used to be released close to departure are usually bookmarked for QF FF members' upgrades, so it nearly impossible to get them now (used to be possible until a couple of years ago).

The best strategy to get QF premium seats now IMHO is to check the calendar frequently and grab the first dates that look like they will work for you, then plan your trip around your flights and hope that you don't need to change anything.