Anemones need very good water conditions, light, and a mature system to really thrive. Some of the non-hosting ones can be kept without ideal conditions such as condys and rock anemones. I've also seen where maxi minis are also not as demanding.
I'm responding to your post so you know where I'm coming from. I have an established tank (15+ years) and am switching from a FO to a reef with one of the prime reasons being to keep at least a couple types of anemones. I have been battling nitrates since I began this transition over 2 months ago and will not order an anemone until I get the parameters where there need to be. I'm keeping some mushrooms and xenia at the moment and they're doing fine, but my system is not able to sustain an anemone yet. You want to have the system that will support and help your anemone thrive so that if it does host clowns, you have a great system for both. Also, if you get an anemone before your system can sustain it, it could possibly perish and cause a disaster in your tank.
I know it's hard to be patient but it is worth it in the long run.