All i normally do whenever i received new 'phones- have a listen straight from the box, just as a starting referance. Then plug them into the computer headphone jack and leave an album playing on repeat for a few days (with a pillow over the 'phones not to annoy the hell out of folks). After a few days just start using them as normal.
Burn-in have a definite effect on dynamic headphones and in-ears (not a single pair which I own or have owned shown a failure to change through burn-in). My Tomahawk also smoothed itself out a bit after 200+ hours of burn in.