Aiptasia is a straight forward plan. Use a syringe to shoot boiling water/lemon juice into its mouth. Products like aiptasia-x and joes juice also work well.
In terms of your cycle, the live rock came in with beneficial bacteria that quickened the cycle, though I would want to see nitrates in your readings unless you are seeing algae or cyano
growth that is consuming it. As it stands, you probably have the bacteria level to support atleast one fish. Having no ammonia readings for 24 hours will prove that. I would wait a day and test again just to be safe.