I do not fully understand the color schemes of chameleons... still learning and I only have one female veiled. But I'll do my best to answer your questions.
I'm assuming she hasn't been mated? If that's the case, it's harder to know when they are gravid. And it's harder to start the countdown to when she would lay. What I have come to understand, is that they are always somewhere in the process of either growing follicles, developing eggs, getting ready to lay eggs, laying eggs, recovery and repeat. (There are probably technical words for these steps, but I don't know them lol).
I had hoped that there would be some sort of corresponding color to indicate what stage she was in, but at least for Ophelia, it doesn't work quite the way id hoped.
What I can tell you, is that you should have a laybin in her enclosure and it might as well be a permanent addition. For O's first clutch, it took her a month from the time she started digging to the time she actually laid her eggs. The second time, there was no warning and it took her a day.
The best things you can do for her, is to provide the best husbandry possible... lights, water, food (look up the care sheets if you haven't already). If you have questions, fill out the How to ask for help form and get feedback on your setup. I keep a calendar and a poop journal with pics.
O started acting strange at the beginning, pacing and climbing the screen. Drove me nuts lol but you want to look for lethargy, not eating, sitting low in the cage, dehydration... those types of things. If you don't have a vet, find a good one now and put some $ aside, just in case.
Good luck and keep us updated!