Personal choice really. If you want to follow the regimen exactly, then you would apply the BP to your whole face, however many people have successfully cleared by only applying BP to problem areas.
I've had the personal experience of having applied BP on my problem areas, only to see that in a few days acne started coming out of my not usual acne battlegrounds. Just keep that in mind if ever this happens to you.
Use it on ur whole face for now. Ive been using bp only in my problem areas for the past 6 weeks and it has been working greatly for me. No problems at all but intially i used it all over ..