I disagree with what chris said^. From what ive gathered, age matters more than weight. A female wont go unless she's sexually mature. Some females dont get to 1500grams. They reach their full adult size at 1200 or 1300grams and produced 3-4 egg clutches consistently. Same way that every female isnt going to hit 3kg's and produce 12 egg clutches. 1500grams is a good guide to go by but it doesnt mean the snake is sexually mature.