Hi. Never having bred any chameleons, I’m afraid I don’t know the answer to your question. However, I would think it would probably be a matter of a couple or few weeks. From some videos I’ve seen, the females do seem to flash gravid coloration to males not long after mating. Gravid coloration isn’t going to tell you if there are any fertilized eggs though…only that she is carrying eggs. To know for certain if the pairing was indeed successful, you’ll need to wait until the eggs have been laid and incubation started. Infertile eggs should show it pretty quickly.