I wouldn't breed a female until it was at least 2 or 3 years old, and 40 to 50 grams.
But my philosophy on that's a bit different from the party line--I think the fat pockets under the arms and the massive tails they can barely lift are unnatural and probably quite unhealthy in the long run.

Males, what you want to look for is a good fat tail coming into the breeding season, as males tend to go off their feed during breeding. Even though they aren't using as much energy as the girls, they still lose some weight during the breeding season.

Sorry jrobinson I would agree with you that a gecko can be bred at the year old mark - leaving it til it is 2 or 3 years old can be a good thing, as age with many animals increases fertility and means that the animal is definately ready to be bred, however it is perfectly fine for geckos to be bred at 1 year old, and over 50g. For a healthy gecko I wouldn't breed it for more than ?4 years, or breed it one year on one year off, otherwise you can risk just tiring the lizard out and having it die younger than it would normally. With older age can also come decreased fertility.

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"If you know everything you may as well blow your brains out because the reason for existence is to learn more everyday." - Mark O'Shea, 2004

Most breeders go by 40 gram rule so they can produce babies to sell at a quicker pace, It is much more healthy for the female if you wait til 50 grams in my opinion.

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Ken
" The United States Marine Corps......sure we are a department of the Navy,,,,,,we're the MENS department "

Some small females will never reach 50 grams without being blatantly obese, however, so I wouldn't make that a steadfast rule.
I'd say looking at the animal's overall body condition, and the width of the tail, is more important than what the gram scale says--at least once they're past age 2.