The apparent efficacy of the current restrictions in Australia seems to be at least 80% effective. The apparent R0 is well under 1.0 and generally the number of new cases each day is dropping. But this is probably not the time to back off. In fact, as NZ epidemiologist David Skegg argues, "it would be a terrible waste [of all the effort so far] if we don’t pull out all the stops now” and maintain lock-down while contact tracing eliminates the virus as much as possible and "tighten restrictions on those in quarantine after arriving from overseas" to prevent re-entry of the virus. After that is done, restrictions could be carefully lifted and business and the economy restarted.
It is informative to plot Australia's new cases each day against a model estimating the percent efficacy of the restrictions supposedly started on 20 March 2020. The actual new cases per day should fall somewhere near the estimated new cases per day for 80% efficacy of the restrictions. From the graphs below, it seems to do that only for about a 40 day exponential wash-in period .
It appears that the wash-in period for restrictions to take full effect may be about 40 days. The 'bump' up above the 80% effective graph line (yellow) may be due to an excess of up to 350 new cases a day from the Ruby Princess.
There are some factors to consider when examining these curves. They presume that the restrictions were started on 20 March 2020 when, in fact, they were introduced piecemeal. And the model assumes that the unrestricted R0 was 2.2, a rough figure that is generally accepted. And luckily Australians were smart and started working from home, often at their employers request, and not sending their kids to preschool and school much earlier that the government and health department 'experts' enforced.