I have asked the same question to my MA and am being told the same. Apparently on my immi account is states...
Required examinations not yet determined
The health examinations required for this person have not yet been determined. If health examinations are required, a link containing the details will be displayed when the person returns to this page.
The home affairs link on one of the above posts is useful and if I am reading it correctly seems to suggest if you have already applied for the visa or if your visa application can take over 6 months to approve then wait for case officer to request medical? There doesn't seem to be a way of getting a HAP iD on my immi account yet. Just says above.
Applied in Nov and the wait is painful!