I think most folks put the hops in the secondary first then rack on top of them allowing the swirling during the racking process to mix a little... you could swirl the carboy/fermentor a little... but not sure if it will make that much difference... i would personally keep it sealed until you are ready to keg/bottle...
A lot of us do primary fermentation only, and when you add secondary hops, you just open the primary, drop them (5-7 days after fermentation has been going) and seal it back up... swirl the neck a little, but again, how much difference will it make?