Welcome to YT!
A great place to find out her due date is
www.debbiejensen.com There's a due date calculator on there. That way you can know for sure!
I haven't experienced my dogs going early, but it is possible. Forgive me, I've just started my cup of coffee, but I *think* someone told me that if they are born more than 10 days early that they won't survive. After that, they have a chance.
Good luck at the vet and keep us updated!