What I would suggest doing is adding the white light overlay at the beginning of the scene, and then changing the opacity to 1 when you need to use it in the scene. Write:
EXT. GRAVEYARD - DAY with WHITE LIGHT_OVERLAY at layer 3 to 0.748 77 161 in zone 2
@overlay WHITE LIGHT_OVERLAY opacity 0
At the start of the scene. Then, when you need it to expand, write:
@overlay WHITE LIGHT_OVERLAY opacity 1
&overlay WHITE LIGHT_OVERLAY shifts to -305 -310 in zone 2 in 2.5
@overlay WHITE LIGHT_OVERLAY scales to 3.178 3.178 in 2.5
I think this is what you meant. I hope this helps!