The omoplata from closed guard is one of the first setups you should master if you’re starting to add omoplata attacks to your game. From https://www.grapplears.com/omoplata, Omoplata 2.0 by
Stephan Kesting and Grapplearts.

Trigger positions make it easy for you to know when it’s time to attack in jiu-jitsu. From https://www.grapplearts.com/omoplata here’s an explanation of the trigger position concept and examples including the armbar, the triangle choke, and the omoplata armlock.