I too go with the 1500 g rule, and will under no circumstance breed one that is lighter. My girl that just layed was 2000 before laying and now shes 1100 right after. She was 1800+ when i paired her.Her eggs were 612 g. She has eaten a bit already so I will weigh her agian soon. Just from that alone I couldnt see breeding a small female just incase that female too lost alot, then her life would be in danger.
I bought a female last year in hopes to breed her, and she was sold to me as a breedable female. She was supposed to be 1300g, so I thought a couple hundered grams gained wouldnt be long. Well this girl was actually less than 1100 and she had eating issues. So for the last year I have been working on her feeding and letting her gain weight slowly. She is now 1400gs. So if she doesnt gain the weight with her normal freedings by fall then she will not be bred.
As far as my pastel, I cant wait till she is big enough simply becuase I want a bee. Some might try to breed her this season, shes close to 1000g but I wont so looks like another year or more before I get a bee.