To have success with an anemone, you really need to have everything stable. That's going to take at least several months.
Then, whether you add coral now or later, the anemone is probably going to move. I've had nems in two different tanks, and put them in what seemed like the perfect spot. Both stayed there for a long time until one morning I woke up, and they were in a completely different spot. One of them proceeded to sting several of my corals during the move. Others I was able to move out of the way before they got stung. That nem never settled down, and I eventually had to rehome it.
The other nem is in a tank where he is the star. I don't have any corals in that tank because I know I can't trust nems to stay put.
I told myself that I could keep them from moving if I focused on giving them the perfect spot to live. I was definitely wrong. Your mileage may vary, but just know that trying to keep a nem and coral might be a constant (and very frustrating) battle.
Then, whether you add coral now or later, the anemone is probably going to move. I've had nems in two different tanks, and put them in what seemed like the perfect spot. Both stayed there for a long time until one morning I woke up, and they were in a completely different spot. One of them proceeded to sting several of my corals during the move. Others I was able to move out of the way before they got stung. That nem never settled down, and I eventually had to rehome it.
The other nem is in a tank where he is the star. I don't have any corals in that tank because I know I can't trust nems to stay put.
I told myself that I could keep them from moving if I focused on giving them the perfect spot to live. I was definitely wrong. Your mileage may vary, but just know that trying to keep a nem and coral might be a constant (and very frustrating) battle.