I was wondering, when exactly does one allocate hits?

before or after the primary opponent makes his evasion action?

I think it's done after the evasion check (Core Rules 226) at the same time when the hit location ist determined - but I'm not entirely sure.

After. If there isn't a hit, you can't make an evasion test.

First you roll your attack, then allocate his based on degrees of success. Then each person who is hit can make an evasion test.