This is a subject that you will get many different views on. Because every animal is different what works for this snake might put this snakes health at risk. That being said I agree with some of the above that a combo of 1500 grams and three years old is a good marker for a starting breeder to look for. I did that this year with my animals where as I could have possibly produced 5-6 clutches this year I held off on three females because they were right there on that border and me being new at this didn't want to risk the health of my snakes for my ability to produce twice as many clutches this year.

This is not to say that a 1000 gram female can't breed and do just fine but there are risks involved if her reproductive system is still not ready you might ruin the animal for ever of breeding. There are many risks for the snakes when breeding.

My advice is to take it slow. Its better to be safe than sorry.