Remember that you don't need to use any skills except stun. Sword Oath autoattack, move when you need to, and interrupt when it's time. You could also assign a special key or button to stun and then reuse that same key / button for any stun / interrupt in any MMO you play. That way, the training you do for stun in this game will help you in other games.

Also, it's preferred to interrupt every eruption, but it's not fatal like ram's voice for chimera. If people get upset because you aren't up to the standards they place on total strangers, ignore them. They're just people on the internet who play games like a job instead of for fun.