Generally the advice is “unlimited” pellets for young baby buns, but I think some members have given their baby buns about 1/2 cup of pellets a day and it was alright too.

Some bunnies get excess cecals from eating too much pellets or chalky pee from excess calcium, while others will refuse to eat hay if they have unlimited pellets available, so cutting back the pellets would encourage hay eating and minimise those problems. Although many places still recommend alfalfa hay with alfalfa pellets, timothy hay has proven to be fine for baby bunnies as long as they’re eating alfalfa pellets to help them grow. In fact, because many bunnies will refuse timothy later in life (alfalfa is tastier), you may want to start giving timothy earlier.