Austrolorp not laying
Australorps are nice birds to have. I think you'll enjoy them.
The australorps that I've raised began laying around 24 to 26 weeks of age. Timing of that first egg depends on so much, including the genetics of the individual bird, its diet, time of year it matured, etc. It's a good sign if you're seeing large, red combs and wattles. If they are hand-raised pullets and have had a lot of interaction with you, they may begin to "squat" when you approach them or reach down to touch them on the back. This is a submissive posture that a hen does when a rooster approaches to mate. I've noticed that my pullets typically lay their first egg within 7 to 14 days of the first "squat".
Are you talking about diminishing light levels, like we have in much of the US right now? Or, are you talking about really low light levels, like would be found in Alaska?
In my neck of the woods (Pennsylvania), light is not needed the first year to induce or sustain egg laying. It would pretty much be a waste of electricity and money. Spring-hatched pullets will begin laying in the fall, when they're around 6 months old. They'll continue to lay for about 12 months, and then go into a fall molt when they're around 18 months old. So, they should begin laying in a couple of weeks, and continue to lay during the fall, winter and into next spring and summer, without any supplemental light.
You're very welcome. After the first "pullet year", some folks use supplemental light during the winter. However, I've never done that. They need to molt anyway, so I give them the time to do it without pushing them to lay. They usually take 2 to 4 months off from egg laying their 2nd year, but I've noticed that some of my hens are continuing to lay during the molt, as I have them on an all-flock feed (20% protein). In years when I kept them on layer feed (16% protein) during the molt, they always stopped laying completely, and it seems like it took forever for new feathers to come in. The flock raiser feed seems to be helping them feather out faster when they molt.