I think we'd need more information about your tank, such as flow and lighting, as well as the inhabitants you're planning to keep. Most anemones need a lot of light to thrive. I personally didn't start even considering anemones until my tank was at last 6 months old. This gives the tank time to stabilize, and will get you used to developing a maintenance routine. Once you have this routine down, and your water parameters are in check (most anemones like relatively clean water) then you can start looking for an anemone.
Once you're ready, suggestion would be to look at bubble-tip anemones (E. quadricolor). They are hardy and readily available, and have many color morphs, though the most common are green and red (aka RBTA = rose or red bubble tip anemone). The key is to get a healthy specimen, which can sometimes be a challenge. While you're waiting for your tank to mature, this would be a good time to learn all you can about the anemone you'd like to keep, which includes learning how to select a healthy one.
Have fun and good luck!