When the male starts expelling sperm plugs he is sexually mature and could mate with your female. Other than mating purposes the male and female don't need to see each other. You need to put a barrier in between the cages such as plywood or an opaque shower curtain. Another thing to consider is after you breed them and you have 30-40 (or more) baby veiled chameleons. I'd be afraid that I would end up having to sell them to a pet store...

It is hard to walk by those tiny cages but Carlton is absolutely right about pet stores selling to our pity. I wanted a tortoise, already had the setup ready and was looking at breeders online. Went to PetSmart for crickets and saw a Russian tortoise pawing at the glass in one of those tiny tanks, dry food, wrong setup. Long story short, I ended up at the checkout line, tortoise in a box.

I love my little guy and am absolutely glad I got him but a week later I went back and there was another Russian in the same tank pawing at the glass. One of the workers saw me looking at him and commented "We never got tortoises but we tried one and it sold after two days so they sent us another one".