[2022] When are damage increase effects applied to a spell with a duration?

Specifically, I am asking about the spell Avalanche with the Wild Path node, which turns it into a 5 second duration spell. If I get an effect that increases cold spell damage halfway through the duration, will that effect apply to the second half of avalanche? Or are effects only applied when you cast it?

I am mostly curious whether Avalanche with the Wild Path node benefits from the damage increases from the Halvars/Last Gift of the Mountain set

Last gift of the mountain:

https://www.lastepochtools.com/db/items/UAzDswTgo

Halvar's Stand:

https://www.lastepochtools.com/db/items/UAzCswTgDiA

I am looking at the affixes on these two that read "Increased (physical/cold) spell damage if you have directly cast a (cold/physical) spell recently". Avalanche is both physical and cold, so it should trigger and benefit from both effects. However, if you take Wild Path and give Avalanche a duration, technically the effects wouldn't be "active" until after you cast it. So do the effects still increase the damage from that cast?