
Temperature taking can help - it's when it drops and stays down that whelping can be expected to start within 24 - 48 hours. I don't however, set that much score by this and certainly wouldn't be sticking a thermometer in her all the time! I go from the first mating, given that conception may not happen immediately either.
Fact is I clear everything, and just be there. It's worrying and frustrating, but all part of breeding I'm afraid.
Once she is in labour, having strong contractions, then don't leave her struggling for much over an hour, each delivery, without seeing a puppy arrive. There's no point letting her become exhausted if at the end of it all, she's going to need a C.Section. I hope she's sleeping in her whelping box, with you in the same room.
Now is the time to call on your mentor to help you through!