Breeding shouldn't happen before she's a year old. During pregnancy she shouldn't be fed too much, but more than the normal 6 feeders everyother day, and all should be dusted with plain calcium without d3. After pregnancy for a few days you should give extra food, water, and calcium.
When placing her in with the male you will know if she is ready or not by her reaction. She will either let the male advance or she could try to attck him/hiss and gape at him.