I think the OP was just trying to get at the age of the females in question. Generally because they will usually not give eggs before their 3rd winter and until they are 1500 or more grams. Its not always the case but its a good rule of thumb. I had 3 females last year that were between 1200 and 1500 grams but they were only 2 years old and did not give me eggs. However this year at 1500 to 2700 and 3 years of age I'm pretty positive I'll be getting something out of them. Hope this answers your question. and yes you can increase your chances with proper husbandry and a good thermostat. Check out J. Kobylka's videos on youtube about ball python breeding, they are very informative.