
My girls start sleeping in it about 10days before the pups are due,during the day they join in with the normal routine.
If they don't settle then I bring them into bed with me after covering the mattress with a shower curtain and Vet bed, I am aware then if they move or anything starts happening,I have CCTV set up but that won't wake me up if she goes into labour.
Don't forget the pigrails to stop Mum squashing a pup against the side of the whelping box.