Take it twice a day every day after that time. The gestation period for puppies is 63 days. This is not carved in stone, but pretty reliable. Keep a record. When it drops to 98 or 99, then rises again, don't go to the movies.
Puppies are imminent.
A room thermometer for the whelping box. F. Some kind of identification. I like to put a different colored ribbon on each puppy as it comes out. This helps keep track of how each one is progressing as time goes on. You will have to change ribbons as the puppies grow, so a good idea would be to get rolls of different colored ribbon on sale somewhere.