Well corals are a bit different than anemones, usually a month after you cycle you can start adding corals. However you will be the ultimate expert on your own tank, therefore you will be the one to notice when alkalinity falls or calcium goes to high, or nitrates start to build. You will need to keep track of all of that and more as your tank matures, you will know its fluxuations and how to control them. If things are stable at the 6 month period then perhaps you may try again with the anemone.
Thomas
PS. Start with easy corals, xenia is a good one, as you learn this coral you will know that you can watch it for water quality problems, sometimes corals just speak to you about your water and for me xenia is one of them.
T