You have enough opinions on her being gravid so I'll just add a few comments and ask some questions...and welcome you to the forum and the world of chameleons!
How deep is the lay bin substrate? It should be at least 6-8 inches.
Here's the way the egglaying should go...
She will of course get fatter in the lower half (or more) of her body, she may drink more, bask more, roam the cage to find a place to dig. Near the day of laying she may slow down on the eating. She may dig one hole or dig several and chose one in the end to dig until she's happy with it. It could take a day or several days with her returning to the branches I between to finish the digging...but she should finally sit, butt down in the hole...likely in the evening and lay her eggs. It may take an hour or two or she may even sit in the hole overnight. When she's done she should fill the hole in and ramp it down and return to the branches hungry, thirsty and thin. At that point you can remove the lay bin and dig up the eggs.
If she doesn't follow what I've said about and instead digs the hole and fills it in without laying the eggs and doesn't dig more (called phantom laying) or sits low in the cage or sleeps during the day or seems lethargic then she needs to see a vet right away....because it indicates egg binding. (Possible if the previous owner didn't look after her right.)
Re the eggs...I'll discuss this later...remind me when she starts digging..ok?