P3 Actual/Forecast Cost

Dear planners;

I need to make the forecast cost histogramme for the schedule, but I am not sure how?

So, I have to make the update on the % progress cost (Actual Cost/Budgeted Cost Quantities) and P3 generate automaticaly the forecast Costs?

OR I have to update the actual Costs and P3 calculate the forcast progress.

Is there any possibilities to keep the progress on 0% (Project start day), and make this job?

Your help will be appreciated.