When does my dog need to see a vet

Is she in labor or has her temperature just changed?

No she is not in labour

no she is not in labour
Her temperature is slowly going down

I'm sorry I couldn't get back on to reply to you.

How is she going today, any changes?
Has she started nesting? (picking out a spot to whelp)

With some b*tches it can be hard to tell when they rare actually going to give birth until they start, some can hide it quite well.
You shouldn't need to take her to the vet unless you think there is something wrong or are you planning on letting her whelp under the vets care? (if so, that's a good idea if you haven't had pups before)