How to configure prefab spawning time?

[MR F1RE FOX]

I need to somehow copy Ancient cane's effect 

if inst.form == "shadow" and not inst:HasTag("INLIMBO") then
   local x, y, z = inst.Transform:GetWorldPosition()
   local xoffset = math.random(-10,10)/10
   local zoffset = math.random(-10,10)/10
   SpawnPrefab("cane_ancient_fx").Transform:SetPosition(x+xoffset, y, z+zoffset)
end