you get the 5s "insight"
effect at the moment you use the skill "concentration"
instantly after you get this buff you should use pyro
if you wait the buff runs out and you have no advantage from it
in my current pyro-pve build i use assassin
with all its rubies ("triumph of reason" and "lord od fear") and cast it permanently on endurant enemies
build is something like this
http://en.allodswiki.ru/calc/#!6!131..31321.3..133..3.3.1....2...2.3.!kpcbuw/AYQMFR!qwrvcwn/CTEWAR!eldomc/UFABLB
but keep in mind this is a "lazy" build so i just need to press 3or4 keys for decent dps, but dps are NOT at maximum this way, i just use it this way since i can respec for free anyway if i want something else
so if you want maximum dps do NOT use this build exactly, change it then