I have a pregnant rat and need to know if she is in labor.?

My rat is around 3-4 months old. I have been caring for small animals for years and just got this lil baby at a pet store and I know she is pregnant but I've only had males up till now so not sure if she is in labor. She has started to stretch out her legs, rearrange her housing, and constantly groom herself. There's been no blood though so I'm not sure if shes just preparing or having complications. I welcome any help at all. Also keep in mind I wouldn't be able to get to my small animal vet till Thursday.