I remove it around 2 weeks in warm weather and pretty much never in cold. In warm weather usually by the time their eyes open around 10 days mine are out of the boxes and I might flip the box on it's side for awhile so they can get back in to sleep. By 2 weeks they are bouncing around and don't need it. They'll just make a pee filled mess out of wood boxes if I leave them in after that. Winter is different though. We had some litters in subzero temps last winter and I didn't even see them until they were 4 weeks. They returned to the box to sleep until 6weeks and by then my doe was having the next litter so the boxes in the colonies were there all winter. I cleaned them and filled with new bedding about every 4weeks and tried to time it for right before the next litter was born. They were in use every day until spring came and then I gave them plastic boxes and sterilized the wood ones.