Wherever you might be, planting or sowing seed as the first rains properly moisten the soil is the most important thing you can do. In the winter-rainfall region this will usually be mid-April to early May. In the summer-rainfall areas it can be a bit more variable, but is usually around September to October. Plants put in once the soil is properly damp usually need no extra water to become established enough to see them through the next dry season. You can plant a bit later into the start of the rainy season, but any other time of year means a huge amount of irrigation will be required to survive the next dry season. And that has the knock-on effect of retarding proper root formation, which keeps your garden dependent on extra watering.