The white will start to show in about 2-3 weeks after born. Beige will also not show up right away. But it should be ok to handle babies and clean. I find sometimes the mom seems to enjoy a break from "mothering". When you put them back though dont make a new nest for her, the mom will destroy the nest you built and make her own, even if you put the babies in it she will push it around and fix it herself. In doing so though its possible for babies to get buried in the bedding. When you put them back too she'll usually go over and pick up the ones you touched and inspect them, clean them etc. She'll even disperse them around the cage but she'll gather them back up once she builds another nest so dont panic