Each chicken is an individual. Breeds do have general tendencies but you have to have enough for averages to mean something. You don't. Australorps have a reputation for being good winter layers, if you had 100 of them you'd probably see that. Breed is the best thing you have to go by but sometimes you have to be lucky.
The flock they came from can make a difference too. Different strains of the same breed can have different tendencies. Each hatchery has their own strain. Each hatchery has their own people selecting which birds get to breed so each flock can be a bit different.
My experiences are similar to Cindy's. My Black Australorps (from Cackle) started laying about 5 months old, mine in early fall. Both of mine went broody in their second summer, just a time or two, not excessive. Mine proved to be good winter layers. But I only had two, not enough for averages to mean a lot.
You just got those two a couple of weeks ago. Sometimes moving them like that will cause them to stop laying and may even trigger a molt. You dodged a bullet there. Considering the move and the time of year I would not be too upset at the eggs you are getting from those two.
I have had some pullets that age start to lay this time of year, I've also had some wait until the weather got warmer and the days got longer. I can never tell when they are going to start laying by age. Even the same time of year they can vary when they start by months. You said they free range. One of the main reasons we think free ranging chickens are not laying is that they are hiding a nest. Can you leave them locked in the coop/run for a couple of days to see if you get more eggs? That might be educational. Patience is probably your best friend in this but you never know. You've seen they don't always lay where you want them to.
Yours free range. In Georgia this time of the year they are picking up stuff by foraging. I'd limit the corn to what they could clean up in ten to fifteen minutes so it doesn't become a major part of their diet and blow their "balanced" diet, but I'd keep doing what you are doing. How are the egg shells of the two that are laying? If they are hard and thick enough you are doing OK, in Georgia it is quite possible you have limestone. They will use that as a calcium supplement for hard egg shells. If your egg shells are soft I'd offer oyster shell on the side. Let your egg shells help you decide if a calcium supplement is necessary or not.
Them not laying in the nests can be aggravating. Fake eggs (I use golf balls) can help but it does not always work. I've had some stop laying in a nest and start somewhere else. I'm retired so I can do this, maybe the weekend gives you a chance. When I have one laying somewhere that is not a nest I catch her on that unwanted nest and lock her in one of my regular nests until she lays her egg. That usually takes about 30 minutes but I had one go 3 hours. Hardheaded hem. Usually once is all that takes and they know where to lay but I had to do that same hardheaded hen two days in a row for her to get the message.
I kind of understand the frustration. I once had to wait nine months for the first of my colored egg layers to finally start. That was the first week of December when all the rules say they should not start. That shows there are no rules. There were three of them and two started laying a couple of days apart. I've had other similar experience but that was the worst.
I don't see that you are doing anything wrong. Your story sounds pretty typical. I predict that in a couple of months you will be really happy with them. Good luck!