Give it a week, or so. You should notice your females coloration change slightly. Search around for some receptive pics, all of my panther females have slightly different receptive colors.
Imho A year old is fine to breed. If you want to wait till she's 18 months, that's fine as well. I wait untill they're a year old and over 60 grams. Those are my prerequisites to breeding a female. If you were to talk to some very reputable breeders they will probably tell you close to the same. In the wild they can reach maturity in 6 months, and I know we are trying to give them the best possible captive lives as possible.