Will it open more Large? Sun Coral?

[NanoCube-boy]

I recent bought a Sun Corals and my feeding hours is 20:00 every night, in the dark. The tank lights shuted off at 18:00, which two hours before feeding time. Right now I'm feeding PRIME REEF frozen food. It's very meaty and has a lot of Coralplankton, which I also added as well. I feed through a couple burst from my waterbottle directly to their polyps.

So Can they open amy more larger than the 2 pictures that are shown? Are they still young?