Not leveling on my cleric but I will say that Sarnak fort in LOIO was always pretty busy when I was there with my druid a month or so ago. Prime time is still US evening and weekends.
I'm not sure what old world and Kunark populations are at now with Velious (since there are always at least 30 people in any given Velious zone now, even at weird times of the day), but for those still leveling, everything should be clear of farmers for the most part.
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What you should probably do is form your own groups, especially for dungeons. As a cleric you already have one of the essentials down, you just need tanks and support. Of course, I say that knowing that forming a group is kind of hard because you have to basically cold-call players. On the other hand, there are a bajillion iksar monks out there in need of a cleric from what I've seen. The poor things.
Good luck!