So after reading this thread again, it appears that others are saying that snails can actually produce eggs before reaching full sexual maturity. Most of us know that when most animals (especially upper class mammals) produce babies before reaching full maturity it's normally not good for the animal themself nor the offspring, so now I'm wondering if snails suffer any consequences from producing while immature?
You are mixing sexual maturity and final size. In many species snails are sexual mature before they are full grown. So they can reproduce and it couses no problems for them. Cluthes could be smaller because of the smaller size of the parent animal.