There is no way to answer this question accurately. Depends on the breed, size of the litter, if there are complications.............
You obviously are inexperienced and I suggest you call a local Vet for advice if you have any questions.
some times it take 2 days but if it takes her longer I'd call the vet
It's hopefully all happened by now, and I hope things are ok. But it might be interesting for you to look at a post I put on a few days ago...
"Pregnancy, Whelping, Puppies -a helpful Web article" on Page 4 of this forum.
There's a link included to a good website which advises.