I always have my Vet take xrays after 56 days.
It sure helps from guessing and worrying.
Give your Vet a call and ask.
Holly will need a shot after whelping and the pups will need their tails docked and dew claws removed. Great time to talk to your Vet if you haven't.
Be careful, always remember a C section may happen.
I never had any problems until I breed Lily. With my Vet we were prepared just in case and twice we had to have C sections. I don't mean to cast a shadow, I am sure your very excited. But one never knows and it is heart warming to be prepared with your Vet.
Good luck