There have been other discussions on this subject. Most comments favour keeping family and friends aware. Many because they think it makes people more Prostate Cancer aware. Many because the family feel it and want to be involved.
I have no close family but I chose to tell no-one and it wasn't hard to conceal my biopsy and being away a couple of days for the operation. As you say having a template biopsy might be something that you can't conceal. Although you haven't got a date and he might have returned to university.
If you feel you should tell him soon then perhaps you should sit him down and have a talk where you're prepared with the information and likely outcomes. Also you might refer him to perhaps this website for information rather than more hysterical sources. I recall being advised to avoid tabloid newspapers and American websites for finding information, things like that might be of use.
I wasn't sure why I should avoid American websites as some of them are very good. Although some are looking for business and offer things that aren't available or recommended here. It was tabloid newspapers that gave me one of my biggest scares during diagnosis so I could understand that.
I'm sure someone with more direct experience will reply. Regards Peter