What he said with a small specification. You need to be the first person to *zone in*, being the ops leader has nothing to do with where the operation starts. Whoever zones in first essentially sets the zone to their lockout.
Darn I had actually typed out exactly what you said and deleted it when I was correcting grammar. Yes the most important part is that you zone in first, as in completely loaded and able to move around in the op instance before anyone else. I've found it still helps to be the ops leader because we've had instances where a leader on a different lockout can be locked out of the instance until lead is passed.