The best opening is : Shadow bolt -> Bane of Doom -> Demon soul-> trinket on use if it's the case->ua -> corr-> haunt-> Bane of Doom.
In this opening, you'll loose 1 gcd reaplaying BoD but you'll gain one great tick of BoD that is more pwerfull than a shadow bolt ( or even 2 shadow bolt) , so it's a dps gain . And the first bane of doom is to start the countdown to the first tick , there the first tick of the second doom ( that will have 5 ticks) will happen 11sec after and not 15 sec.
if you're trinket didn't proc after you cast haunt, wait for BoD and cast a shadow bolt till you have all you're proc , you have 10sec to reapply BoD so take the more profit
.