The Elbow Push is an important technique that all advanced grapplers know, but teaching it can be difficult because of the timing needed.
To teach the Elbow Push I like to pair it with the Stacking Pass because it elongates the timing allowing for better practice AND the elbows are in a static position, meaning the beginner doesn't have to go find the elbow as the person is moving to side control.
Once a student becomes proficient at doing it like this, I will then start teaching them from side control bottom with more dynamic passes from the assisting student on top.