As a side note,
hese kind of opener also assume you won't be moving (which is usually the case)
If you're doing a fight where there are high chance you'll be moving in the first minute, you might want to hold on triple cast and swift cast.

Triplecast + fire IV only make you save the tiny bit of extra cast time vs the GCD. (not even 1sec in the end).

If you know you might be moving, hold it. You'll save more dps by being able to cast a sibgle fire IV while moving than 3 fire4 while standing.