Hi there.
The only advice I would give is that I have always been told that hormonal rat aggression in males - the sort that can be treated by neutering - usually starts at about 6 months old. So the behaviour that your troublemakers are showing may not respond to neutering. We have had a few boys neutered at different ages, but it was more to allow us to house them with females, not for hormonal agression. So I can't really speak on the effectiveness of having it done for that reason.
By the way, just out of interest, neutering makes a huge difference to buck grease. We found it pretty much went away completely after neutering.
The only advice I would give is that I have always been told that hormonal rat aggression in males - the sort that can be treated by neutering - usually starts at about 6 months old. So the behaviour that your troublemakers are showing may not respond to neutering. We have had a few boys neutered at different ages, but it was more to allow us to house them with females, not for hormonal agression. So I can't really speak on the effectiveness of having it done for that reason.
By the way, just out of interest, neutering makes a huge difference to buck grease. We found it pretty much went away completely after neutering.