In SE Qld you can sow your annual herb seeds pretty much at any time. They'll need protection at this time of year (summer) from extremes of heat, and they'll grow quite quickly, so they might have a shorter than normal life cycle. But that doesn't matter, because most of the annual herbs, like basil, will often self-seed, so you've pretty much got a constant supply all year round, unless you're out west-ish, and you get frosts. Keep your seedlings in dappled shade during the hottest time of the year, and gradually harden them up until they are mature enough to take the hottest sun. If you do this, your basil may even defy Nature and go on for a couple of years or so. This is a wonderful climate for all but the cool-weather herbs. (Things like rocket or coriander really bolt to seed here in the blink of an eye, so are best grown in winter.) Give them plenty of water, but remember that drainage must be excellent to survive our torrential downpours in summer.