The absolute quickest way to get Qantas points is from actually flying. The points generally appear within an hour or two of your flight. As you already know, Qantas Wine is also very quick to credit your points. After that you’re probably pushing it. Even if you signed up for a credit card that is quick to credit points (eg. AmEx) and you met the minimum spend more-or-less immediately, it would take a bare minimum of a week to 10 days to go through the process of application, application approved, receiving your card, activation, spending, receiving the points.
I haven’t received Qantas points from eBay for a year or so (I now credit my eBay spend to Velocity) but from memory it takes a month.