Congrats! I found that my EE's first egg or two were not the true color she was going to lay. Mine first laid a mix between green, blue, and grey. Now there's no mistaking it for anything other than a gorgeous shade of green
White egg layer + blue egg layer = possibility of blue eggs
Brown egg layer+ blue egg layer = possibility of green eggs.
Chocolate egg layer + blue egg layer = possibility of olive eggs.
Blue coloration is throughout the entire shell, bown coloration is added on top of the shell. Birds with brown egg genes AND blue egg genes basically add a thin layer of brown over the top of the blue causing the egg to appear green I believe.
My first EE laid a beautiful rich sky blue egg. My second laid a HUGE mint green egg. A third laid brown.