Material help

Hey everyone so I am trying to figure out how to get a material to “fade” in after the player collides with a button. I have gotten the whole thing set up but, the issue for me is that when the player enters the volume, the Decal just pops into existence.

I believe I can do this with a timeline node but, that would be with a gradual fade in and out. I’d like to have it sort of pan into existence though. So stuck trying to figure that one out.

So if someone can post something similar I can look at it and see if I can recreate it for myself. XD