May. Just insert the cloves, plate down, just under the soil. It's also the right time to start planting that other allium associate, the onion. There are so many onion varieties available in Australia now. You might have to look around for these in garden centers or try mail order. What makes these onions interesting is the way they multiply.
Egyptian onions are different.
Make sure you add a little lime or dolomite to the soil a couple of weeks before planting garlic or onions. They love the sweeter soil and will benefit from it. Here in Queensland your tomatoes should be coming into their own. Leafy vegetables, like broccoli, cabbage, cauliflower, asian veggies and lettuce are nitrogen hungry. Feed them with liquid manure or fish and seaweed fertilizer.