Controlling time on a Continuous Animation on Essential Graphics

Hi from Portugal, 

I'm trying do to a after effects template to use it on Premiere and this is animation.

I do woodworking tips and triks on youtube, and this animation it's like a loading bar, so the user knows how long every trick takes. The problem is this animation is not the typical Essential Graphics animation with the (animation in) - (no anomation) - (animation out).

This is a continuous Animation that can take 5,10 or 15 seconds with 2 simple keyframes (scale-x 0%) - (scale-x 100%)

I know i probably have to add some Expressions to it so i can add it to Essential Graphics controls so i can use it on premiere. 

Can anyone help me? 

tks

Rui