It can be as early as 5 or 6 months, mine never laid until they were a year+.
Do you mean how fat is the animal?
Their are several indicators that your female may be cycling an infertile clutch, they don't always look pregnant (although mine did)
There are a couple of articles on the "Raising Kitty" site that talk about what to look for:
Breeding, by Mike Monge and the article on females by Lynda Horgan.