Signs That a Female Discus is Carrying Eggs?

Hi, I have advanced freshwater systems and I'm starting to breed discus. I currently have 5 discus, 2 breeding pairs, and a blue diamond waiting for a man, they're spread out between 159 gls. One pair has a 3 1/2 inch female and a 4 inch male, it's clear to see from their behavior that the female will lay eggs probably in the next month or less. I've been searching for any information on the physical traits of a female discus carrying eggs and have had no luck finding anything. There has to be some type of sign that she's carrying eggs and some way to tell when she's ready to drop them, besides when they start preparing the nest.
Can anyone help me out? Any information would be greatly appreciated, Thank you!!!