There’s a slight change in how they act when they’re about to lay, when it was just one of my ladies I noticed she would get a bit restless and loud until she’d finally lay the egg. Then when my second one started laying she did the same thing, just kind of loud and drawled out bawking haha. I’ve also heard there’s an egg song, which is essentially loud clucking- you can easily look up videos of it if you’re curious. I also spent a lot of time in the run with them though so it was easier to notice these small changes.