I've been popping it before Brutal Shell, and then using a Burst Strike before Solid Barrel. It gets all my buffs cycling faster, and sets me up so that No Mercy, Sonic Break, Blasting Zone, and the Renzo combo all queue up for Trick Attack. Leveling from 70 to 80 with a NIN helped me a lot in workshopping an opener that gets the most bang for every cartridge.

Seems to be working pretty well so far in EX primals. I've been beating every pug tank I've come across yet, and I'm constantly rubbing shoulders with my DRK friend that I plan to go into Savage with.