Once you have gone through all of the other steps outlined above, you will be in a position to list some of the initial privacy impacts, risks and vulnerabilities that the project might present. This is an initial view which you can use to inform how you complete your PIA, what questions you ask stakeholders and what problems might arise during implementation of the project.
However, you must be clear that this is merely a first attempt at identifying privacy risks and has been very much considered from the perspective of your organisation. During the PIA stakeholders might raise concerns that you have not considered or might put much greater weight on concerns you identified but dismissed.