They should, once they get approval to reopen, and taking into account the fact that they won't be making a profit that first week or two anyway, make the first couple of openings a "Family and Friends" day, just to make sure they've ironed out any kinks, and can find any implementation issues.
Because there are always kinks.
Then hold a media day with journalists, and maybe local people of influence (bloggers, people from here and other sites like it), who can confirm that the plans are working. That gets them media coverage about doing the right thing without taking anything just on the word of people with vested interests of the park being open, meaning that more people will potentially be willing to come to the park.
Hell, make it an invitation to the Dreamworld management as well. It's not like their Covid plan will be a trade secret as everyone's will basically be variations on the same theme, and for this kind of thing the optics of the parks working together for the benefit of the public at large can only be a positive. If they can make it happen, invite management from all the popular parks. That might be harder due to travel constrictions, but it seems reasonable that this could count as necessary business.
But there is no way you'd do the media day first, because if something does go wrong, that will set them back weeks, or maybe even months in the view of the public.
This applies equally to whichever of the parks is going to be able to be the first one to open.
But who knows, maybe the different park management groups are already working together. A rising tide raises all boats, after all.