I don't actually have trouble with the timing. It's that Souls games, to my knowledge, made it somewhat clear which attacks could be parried. Large enemies could obviously not be countered, as all you have is a somewhat small shield. Regular attacks with normal weapons usually could be countered, but the problem was always that the timing was really strict.
With bloodborne, it's more "try it out until you find attacks you can counter", but it's not always the same. There was a large enemy that would jump towards me and I shot it in the air, staggering him. I did that to a different large enemy and he not-so-gently lowered his weapon onto my face. If I use it, I make sure I try it on attacks I can still dodge if it doesn't work. Not willing to take too many risks.