Help with longsword

I have played subreak and world, and when starting wilds o decided to try out a new weapon and I decided on the longsword. I have 11 hours of playtime and currently fighting the black flame. While I am loving the weapon I keep having the same problem with the counters. Because they need an attack before for them to work i keep misjudging the time I have and keep getting hit. It got clear now while i am fighting the black flame because it has both quick and slow attacks, it comboed with my pc not being the best, makes the fight a complete nightmare to me. To the veteran long sword hunters, do you have any tips and ways to train the timings? Because i find the training ground's attacks way too repetitive to learn.