Nice to see your retifers are doing so well. You female is obviously mature, is your male there yet? You'll know if the egg isn't viable because the yolk will drop. The yolk will also lose its round/oval shape and more flat along the top. When you rotate it, the texture of the yolk will seem "chalky." If it's viable, the yolk will keep its shape and a vein will appear. Eventually you'll see something twitching off the yolk.
Viable or not, it's really cool to see your post.