Assuming that Sheila is involved in the Kurta massacre, why would it take more than a year between her meeting Kurapika and the Kurta massacre?

There are some really cool theories about Sheila being involved in the Kurta Massacre. Some say that she's Pariston and the main culprit while others say that she's part of a human trafficking gang. And there are probably many more theories about Sheila.

I just want your thoughts on why it would take more than a year if she was involved. Why wait?