when the females hit a good weight and start ovulating....
but seriously, there really isn't a "breeding season" for geckos in captivity. but usually most people start pairing very late in the year, like mid to late december. some actually breed year round as well. we pair up late december, early january, and are still getting eggs in july from some of our late breeders. all of our males are seperated for the year, but we have a couple of girls that seem to have retained sperm. we won't pair any more up again until late december of this year.
We keep our pairs together all year round. From October on we will give them less food and shorten the light hours, so they get a cooling period.
From February we start giving them more food and turn the light hours up again. They will start producing again from that time. So the breeding season here is from February till October.