Ken's son is 36 and have been urging him to get a PSA test at least for a baseline since his grandfather had it and now his father. But so far no deal! He is self-employed and doesn't have the greatest insurance, so it is a struggle trying to convince him!
I too think if there is a clear history of it in your family, the earlier testing the better!
Ken started testing at about age 50, but wasn't until in his sixties that it started being a concern. His dad got in is his 70's. So i think his son is thinking "well, i won't get it until much older!"