You said that you have had your female for about 4 months and that she was 2-3 months old when you got her...so she would be about 6 or 7 months old now and would have been about 6 months old when the two were together for a couple of days...so might be possible that the eggs would be fertile....or there could be some that are fertile and some that are infertile.
I find it strange that there are no mustard/orangey/brownish markings on her....or torquoise/blue spots.
You said..."I have now put in a plantpot with some sand kind of stuff the reptile shop I bought her from suggested! is that okay?"...for many years now I have used washed playsand and had no females refusing to use it...and no health issues from them using it....but other people use other substrates successfully too.
You said..."How long should I wait until her behaviour requires a trip to the vets? she doesn't look at all stressed, she's a beautiful colour (as always) and her eyes are showing no signs of stress or dehydration (nice and round) She's still eating and drinking fine"...you said that she was digging...so hopefully now that you have given her a better place to dig she will dig there and lay the eggs. They can dig the same hole for more than one day or they can dig a couple of test holes before settling on one. If they don't settle on one hole, then it means that they are not happy with the site. Do NOT let her see you watching her when she is digging or she will abandon the hole. If she abandons it often enough it can lead to egg binding. Some of them stop eating a couple of days before they lay the eggs and others will continue to eat. Things to watch for are....no longer digging, but didn't lay the eggs...digging a hole, filling it in but no eggs are in the hole when you dig it up...lethargy, sitting on the floor of the cage all the time, sunken eyes, etc.
You asked..."Should I increase the amount that I mist her cage?"...I have found that the few days before they lay the eggs they are more thirsty...but you don't want to disturb her any more than necessary right now...so if you mist, try to do it when she is up in the branches and leave her alone if she is digging.
You said..."I've never had to deal with a chameleon laying eggs before, would have obviously done all of this research sooner if she'd shown signs!"...even if you had done the research, its still nerve-wracking (sp?).
FOR THE FUTURE (I wouldn't try it now)...usually if you show the female to the male, she will darken the background colors, hiss, sway back and forth, etc. when she is gravid/non-receptive and can see the male.
Let us know how things are going, please.
Good luck...hopefully she get through it well!
