I like to start around 1,400. I got a female pied once who was 2 years and 1000 grams when I got her and the guy told me after I'd already received her that he'd paired her with a male that season (so she was probably only 900-950 at the time). As it turns out 1000 was her gravid weight and she laid two eggs and two slugs a month and a half later. Thank goodness she ended up okay (I was worried about egg binding). However after what was a perfectly normal incubation (no temp or humidity issues) both viable eggs ended up with highly deformed hatchlings that had to be euthanized (face under developed, organs on the outside). I don't know if her low weight or age caused the deformation but I'd never breed at 1000, but over 1,300 and a good age should be fine.