I have yet to see more N class seats becoming available closer to "the date" (why would or should they do it anyway?). If you have a particular set of segments you want (and the segments are allowable for the fare), you may be better off using an agent or QF direct and paying a slightly higher fare (ie not N class). The N class fares have segments totally up to the internet computer to select - the QF reservations agents won't touch them.

If you REALLY want status credits, it is not uncommon for people to buy a J class ticket SYD ADL and go via CBR and MEL. That's 30 SC per segment (total 90).