Your chameleon will become chubby and often you can see the eggs laying just under her skin, she will become restless and start digging in the corners of her cage, she may go off her food, she will show a darker coloration (with often spectacular markings!) and she may be moodier than usual. This can occur at 5 months of age and older.
Unfertilized eggs do not hatch. When you dig them up you can throw them away, but having said that, if you breed her once she can lay a clutch and then lay another clutch later on as a chameleon can retain sperm for up to a couple additional clutches, so if that's the case don't throw those second set of eggs out!
I've seen some very INappropriate egg-laying container put into an egg-laden female cham's cage--it was a sandwich container no more than 1.5 inches deep. So, just in case you don't already know what they need, maybe it would be helpful to point you to a helpful post on egg-laying bins: