As a relatively new-ish reefer myself, I can tell you I just used aiptasia-x two days ago (on the recommendation of the forum...thanks guys!)
It's super easy and you'll be fine.
I treated in the tank, being careful not to get any on corals, etc (though it doesn't sound like you have anything else yet in your tank, so not an issue for you). It was fine.
Then, I went with a red flashlight at night to see if there are any more. Did this for a couple nights. I'm sure they'll pop up at some point, but then I can aiptasia-x them again.
Actually, now that I think about it, if all you have is live rock in your tank and you're beginning the cycle, this might be a great, easy, risk-free time to get out that Aiptasia-x and really zap any of those that are in there.
It's around 15 bucks. A local fish store will have it. You'll be fine.
Alternatively, I had another aiptasia on a rock that I could easily pull out of the tank. I did so, and then I used a pair of lineman diagonal cutters (this is the poor-man's bone-cutter, available at any hardware store...just clean it before and after) to remove the aiptasia and the chip of rock it was anchored to. It went in the trash. Make sure you snip off the chip of rock, too, to get it all. I bought aiptasia-x afterward because the second one was on a rock that wasn't removable.