AF/UI removal is on cast, AF/UI buff is on hit. If you look close enough, the buff gets removed slightly before the cast bar fills up. This change was made in 2.1(?) to prevent "infinite" Flare AoE.
Printable View
To be fair, if you have 400 ping, its probably because you're not in a server close to you. Even if you're there for friends or somesuch, it's kinda on you.
Also, I get about 2 seconds of leeway if anything refresh doesn't happen after Fire IV x3 and Fire. What's your Spell Speed? I usually hang around the 1700-1800 range.
The best QoL I could ask for a BLM is just deleting enochian as an action and put it as a trait. The revamp the BLM got make enochian useless as an action and it should just activate if your lvl is high enough and you're under fire or ice.