Why do the PA first?
The COS suggests you complete the PA before you attempt the OA. I am relatively new at WGU (started 4/19) but have been teaching this material at other colleges for many years. I assume the course designers have a reason to suggest doing the PA first. However, the only benefit I can see to that path is that you will have practice applying a method of analysis to your research question.
That will give you a deeper understanding of the chosen method. And if you choose a statistical analysis method, practice interpreting a p-value and test statistic.
It is possible that you may get a better understanding of more than one method if you ‘audition’ research questions/methods as you try to find the question you choose to use in your tasks.
If you do decide to do the PA first, know that you are in the majority – about 60% of my students choose to do the PA first. I have only anecdotal evidence at this point, but my sense if that both groups do equally well overall.
If you have had a previous intro stats course, or have some background in data analysis, then doing the PA first makes sense to me. That is the standard path. If you have not had statistics or experience doing data analysis, I recommend reading the entire MindEdge textbook before diving into the tasks. That will give you a better understanding of what the analysis techniques can do and help you come up with a workable research question.