Well, that was helpful, huh?

Of the 9 responses you got so far, the average is 8.5222222 watts, so set it at that!
Seriously though, the best thing to do is just begin at say, 7 watts. If that doesn't vape well, then go ahead and bump it up a notch. The 30s is pretty forgiving; I haven't gotten a burnt hit from any of mine yet. Good luck.