For yours, I would recommend making the center 3x3, as I believe the shrine will be placed in that center area. I could be completely wrong as to how it works, but if that is the case, it would be off center with a 2x2. Its just a small change, simply extending sides out and such.
I'm not really sure about that:
Xwaffle wrote:I'd keep it 16x16 - 24x24
I made another one: