Definitely add the trigger last, those picasso's are very aggressive!
My eel is fairly even tempered, in fact i hand feed him. Caution on adding anything small after the eel! shrimp should be added before the trigger or eel too! I added a $12.00 shrimp which lasted a good hot 5 secs in the tank, after a 2 hour acclimation, thanks to the picasso! So Beware!

Good luck with the tank