Waiting 6 months is not good advice. It is about stability. I've had success adding anemone in a new tank and they're still alive today ( over a year). It is important to understand water chemistry and how to keep that stable. For example, if you add little live stock in the beginning and then starting a lot of life stock after six months, your water chemistry will not be stable.
This question also depends on what kind of anemone you would like to keep. Haddoni require deeper sand bed as they like to dig their foot in sand. Gigantea likes high light and high random flow. Magnifica requires high light and high flow as well and it is recommended you create and island with a flat service where they cannot move on the glass. People have more success with tank raised btas than wild btas.
You'll need to nem safe proof your powerheads. Large carpets can flood your home when they cover overflows. Are you ready to have hospital tanks so you can treat sick anemones.
There's a lot more info

. But with dedication and understanding their needs and stability, you can have success