Changing bedding after kits are born

How soon after kits are born do you need to change the bedding? I changed mine like 2 hours before the babies were born, she was showing no sign of labor and had not yet nested....I thought it was odd as she has had a couple of litters before and started to nest like 4 days before giving birth...Should they be brought in the house? they are in a cage with a hutch outside.