We’ve stayed in Perisher a few times on the first weekend of the ski season (the June long weekend). Apart from doing the Porcupine Rocks walk, we also walked once to Blue Cow in very wintery conditions. It’s along a road, so although it is recommended for summer, I think early winter before heavy snowfall is a more picturesque but still practical option.
This walk is included in the Kosciuszko southern section walks brochure, number 13. And Google seems to know the way. I’ve also included a couple of photos of snow men that a few of us made later that day. Looks like it was a good start to the ski season.