Player scaled pets and damage buff procs

Hi,
I was debating the changes to the conduit of destructive whispers in another thread, when a bit of a worrisome thought has invaded my mind and claimed annexation.

Suppose I have some Mortar Traps, 100% elemental to chaos conversion active, and I trigger the Hungering Void proc. Now, I understand that the player damage conversion transfers to the player-scalled pets, and Mortar is considered one, so fire damage from Mortars becomes chaos, which then can be amplified by Hungering Void proc.

But what happens to the damage of the Mortars that were placed before the proc has triggered?
Does it go up regardless, or does the bonus damage from Hungering Void only applies to the Mortars placed during its duration?

Similarily, the elemental->chaos conversion - does it happen regardless of when the conversion was toggled, or should I make sure I first toggle the conversion and only then place Mortars?