This has probably been answered before, however I didn't find anything in my minimal searching. This is either because I'm bad at searching, or because its early in the morning.
That being said. Chaos bolt can be a slightly long cast, and timing it with your Procs helps it's damage quite a bit. So when does it decide if it should use your updated stats from a proc? Is it decided when you start the cast of your spell? When the spell stops casting and starts flying toward your mob? or when the spell actually lands on the mob itself? Just curious if I have like 1.5 seconds left on a proc, should I try to squeeze in an extra CB, or should I hold it for my other procs to pop again? (specifically noting that I'm not close to capping embers seeing as I just came out of a burn)