Jaundice in preemie

My son was born with jandice he is doing well with eating and breathing on his own i will be discharged today frim having severe preeclampsia after giving birth via classical C section....he went str8 to Nicu and was in a regular crib and then two days after he was put under a blue light for jaundice im wondering how long this process takes is it diff dor each child and is this something common with alot of preemie s?