The Age of Sexual Maturity in Rabbits
Due to the great variations between rabbit breeds (including variations in size and weight at adulthood), there are also variations between the times at which certain breeds reach sexual maturity.

On average the smaller breeds will mature faster than larger breeds. In addition, within certain rabbit breeds there is also variation between the varieties of that breed.

It has also been observed that does will usually reach sexual maturity thirty to sixty days earlier than males of the same breed and variety. Below is a guideline for the age at which breeds tend to reach sexual maturity:

Miniature breeds: Netherland Dwarf, Dwarf Hotot, Polish, Britannia Petite, Holland Lop, and other similar breeds

Reach sexually maturity at 125 to 150 days of age.

Medium breeds: Florida White, Dutch, Mini Lop, Havana and other similar breeds

Reach sexually maturity at 150 to 180 days of age.

Large breeds (Commercial or Standard breeds): New Zealand, Californian, Champagne d’ Argent, Palomino and other similarly sized breeds

Reach sexually maturity at six to seven months of age. Many commercial breeders will mate young does when they reach a predetermined weight rather than breeding by age only. Commercial breeds, depending upon the strain and other factors, will mature when approximately nine to ten pounds body weight.

Giant breeds: Giant Chinchilla, Checkered Giant, Flemish Giant, French Lop and other similar breeds

Reach sexually maturity starting at eight months of age.  The reason for the delay in maturity is that these animals will not attain their overall physical development until approximately this age.

Most rabbit breeds will continue to mature and grow even after they reach sexual maturity. If rabbits enter production at an early age they will most likely not reach their maximum adult size. Yet, that does not affect the potential size of their offspring.

So, imagine a male and female rabbit who both have the potential to reach 12lbs when fully grown. If they are bred at an early age they may only weigh 9lbs when they are fully grown. However, you can assume that their offspring will have the potential to reach 12lbs if the offspring are allowed to mature (not breed at an early age).